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CatalogIntroductionⅠ AAAA Battery Basics    1.1 What is the AAAA Battery?    1.2 Types of the AAAA Battery    1.3 The AAAA Battery UsageⅡ AAAA Battery Features, Specifications and Replacement    2.1 Features of the AAAA Battery    2.2 Technical Specifications of the AAAA Battery    2.3 Non-Rechargeable AAAA Battery    2.4 Rechargeable AAAA BatteryⅢ 4 Benefits of Powerful AAAA Battery    3.1 They Have a Great Power Output    3.2 They’re Excellent for Practical Everyday Use    3.3 AAAA Batteries are Environmentally Friendly    3.4 They Have a Durable, Heavy-Duty StructureⅣ The Best 4 Types of the AAAA Battery for You to Choose    4.1 What to Look for in AAAA Batteries    4.2 Best Overall: Energizer AAAA Alkaline Batteries    4.3 Best Value: AAAA High-Performance Alkaline Batteries    4.4 Best Rechargeable: EBL Individual Smart Battery Charger with 4 Pack AAAA Rechargeable Batteries    4.5 Streamlight Stylus AAAA Replacement BatteriesⅤ An AAAA Battery Can't Replace 2 AA BatteriesⅥ FAQ1. What is the AAAA Battery Equivalent?2. Where to Buy AAAA Batteries?3. What is the AAAA Battery Used for?4. What are the Differences Between AAAA and AAA Batteries?5. Are A23 and AAAA Batteries the Same?6. Are E96 batteries AAAA?7. Can I Use AAA Battery Instead of AAAA?8. Where Can I Buy AAAA Batteries?9. How Much does the AAAA Battery Cost?10. How Long can AAAA Batteries Last When Unused? 11. Are the 18650 and AAAA Batteries the Same thing?12. What are the Best Rechargeable AAAA Batteries?13. How to Install the AAAA Battery in Your Device?14. What is the Smallest Battery?IntroductionThe AAAA battery (also known as quadruple-A) is 42.5 mm long and 8.3 mm in diameter. The alkaline cell weighs about 6.5 g and produces 1.5 V. This size battery is also known as R8D425 (IEC) and 25 (ANSI/NEDA). This size alkaline battery is also known as Duracell type number MN2500 or MX2500, and Energizer type number E96.This article will tell you all you need to know about the AAAA battery.video:show the free AAAA batteryⅠ AAAA Battery Basics1.1 What is the AAAA Battery?The AAAA battery is a tiny cylindrical cell alkaline battery. The AAAA battery is a reasonably common battery that is manufactured by a variety of prominent companies like Duracell, Atomic, Energizer, and others. Smaller firms and private label battery manufacturers also produce a lot of AAAA batteries. Other businesses make batteries that are comparable in size to the AAAA but have various names and capacities.1.2 Types of the AAAA Battery Zinc–carbonAlkalineNiCdNiMHLi-ionIEC nameR8D425LR8D425KR8D425HR8D425 ANSI/NEDA name25D25A   Typical capacity300 mAh500–600 mAh 325–500 mAh160–170 mAhNominal voltage1.50 V1.50 V1.25 V1.25 V3.7 V1.3 The AAAA Battery UsageAAAA batteries are widely popular and are ideal for applications that require a small but stable battery. The following are some instances of AAAA usage.Medical Devices and InstrumentsCalculatorDigital ThermometerLaser PenSecurity System PanelFlashlightElectronic ToysBattery Pack Application Smoke Detectors Memory BackupA 9-volt battery is opened to reveal six LR61 cells, which are comparable to AAAA batteries.These batteries are not as popular as AAA or AA batteries and, as a result, are not as widely available.Some alkaline nine-volt battery versions have six LR61 cells joined by welded tabs. These cells are comparable to AAAA cells and can be used in some devices in their place, although being 3.5 millimeters (0.14 in) shorter.Ⅱ AAAA Battery Features and SpecificationsAAAA batteries are small, cylindrical batteries that are widely found in small electronic devices such as calculators, flashlights, laser pointers, game consoles, and others.AAAA batteries, like similar but bigger AA and AAA batteries, are available in a variety of chemistries, each with its own set of performance and features, as well as a range of pricing.2.1 Features of the AAAA BatteryAAAA batteries have physical dimensions of 8.3 x 42.5 mm (0.3268 x 1.6732 inches) and are extremely similar to:AAA battery dimensions (D x H): 10.5 x 44.5 mm,AA battery dimensions (D x H): 14.5 x 50.5,except for the AAAA, which is often smaller and longer/thinner.AAAA batteries have numerous labels, including LR8D425 (alkaline, IEC standard),  KR8D425 (NiCd, IEC standard), R8D425 (zinc-carbon, IEC standard), 25A (ANSI standard), HR8D425 (NiMH, IEC standard), MX2500, LR61, Mini, and many others, but almost all manufacturers use the 'AAAA' label to avoid any confusion.Note: Although the true LR61 battery is slightly shorter (3.5 mm, 0.14 inches) than the AAAA battery, several manufacturers identify their AAAA batteries as LR61 batteries. LR61 batteries are rarely used on their own; instead, they are frequently combined to make bigger batteries, such as 6V (4LR61) and 9V (6LR61) batteries.The chart below lists the most common chemical types of AAAA batteries:ChemistryZinc-CarbonAlkalineNickel-CadmiumNickel Metal HydrideLithium-IonRechargeableNoNoYesYesYesTypical Voltage1.5 V1.5 V1.2 V1.2 V3.6 VTypical Capacity300 mAh400 - 600 mAh200-400 mAh350 - 500 mAh170 mAh2.2  Technical Specifications of the AAAA BatteryAAAA Battery Nominal Voltage1.50 VoltsCapacity≈  500-600mAhOperating Temperature0°C – 60°C Diameter8.3mmHeight42.5mmChemistryAlkaline 2.3 Non-Rechargeable AAAA BatteriesNon-rechargeable alkaline AAAA batteries with a nominal voltage of 1.5 volts and a capacity of 400-600 mAh, or even more, are the most prevalent.The actual capacity is determined by the discharge current as well as other discharge parameters. The Energizer AAAA battery, for example (PDF datasheet, opens in a new window), has a capacity of:250 mAh when discharged with 300 mAh current325 mAh when discharged with 200 mAh current475 mAh when discharged with 100 mAh current680 mAh when discharged with 10 mAh currentAlthough zinc-carbon AAAA batteries are less expensive than alkaline AAAA batteries, most manufacturers choose alkaline AAAA batteries due to their superior performance, which includes a more steady output voltage, greater capacity, and longer shelf life (up to 5 years).2.4 Rechargeable AAAA BatteriesNickel Cadmium (NiCd), Nickel Metal Hydride (NiMH), and Lithium-ion batteries are the most common rechargeable AAAA batteries.Because cadmium is a heavy metal and a harmful contaminant, nickel-cadmium (NiCd) AAAA batteries are rarely used anymore.NiCd batteries have a very low internal impedance and can easily provide high currents. They do, however, have a relatively high self-discharge rate, a very strong memory effect, fewer charging/discharging cycles than NiMH batteries, and a lower overall capacity.Furthermore, both NiCd and NiMH batteries have a nominal voltage of 1.2 volts; several devices designed for 1.5V zinc-carbon or alkaline batteries do not function consistently when powered by 1.2 volt NiCd and/or NiMH cells.Actual capacity varies depending on discharge conditions and battery age, although it is often less than that of NiMH batteries.NiMH batteries are preferred over NiCd batteries due to advances in chemistry and the fact that NiCd batteries contain cadmium.Nickel Metal Hydride (NiMH) batteries can withstand more charging/discharging cycles than NiCd batteries and have virtually no memory effect. Furthermore, NiMH batteries have a lower self-discharge rate and a higher capacity.NiMH batteries are the preferred 1.2-volt chemistry for AAAA (and other) batteries since they do not contain hazardous heavy metals.Ⅲ 4 Benefits of Powerful AAAA BatteryFinding AAAA batteries that suit a compact device is one thing, but do they give enough power and lifespan for your needs?It's always inconvenient to have to replace batteries after such a short length of time. That is why it is recommended to seek out the highest quality possible.AAAA batteries (also known as Quadruple-A or LR61) are smaller than the more common AAA and AA types. They power small devices like LED penlights, glucose meters, laser pointers, headphone amplifiers, and powered computer styluses.Despite their small size, they can pack up to 1.5 volts of power in a slender cylindrical cell that is 42.5 mm in length and 8.3 mm in diameter.See how the AAAA alkaline battery compares to other models in terms of general characteristics: Battery TypeLengthDiameterUsesAAAA42.5 mm8.33 mmLaser pointers, LED pen lights, styluses, etc.AAA 44.5 mm10.5 mmTV remotes, cameras, MP3 players, Bluetooth, etc.AA 49.2 mm–50.5 mm13.5 mm –14.5 mmToys, remote controls, clocks, etc.C50 mm26.2 mmTorches, toys, etc.D61.5 mm33.2 mmLarge torches, transistor radios, etc.F91mm33mmHigh current devicesNow that you're more acquainted with quadruple-A battery cells, let's look at the advantages of these little yet important power sources.3.1 They Have a Great Power OutputThe alkaline battery technology utilized in quadruple-A battery cells has a capacity of 500–600 mAh, with non-rechargeable variations having a much lower discharge rate.This implies they can be used for extended periods in electrical equipment, particularly those that consume minimal amounts of power.According to a comprehensive study conducted by Battery University, alkaline-based batteries often have lower discharge currents, resulting in long-lasting performance over their usage period.AAAA alkaline batteries are normally made to last a long time. The addition of graphite, zinc, and manganese in the manufacturing process increases the density of each cell. This allows them to deliver tremendous power even at nominal voltage.3.2 They’re Excellent for Practical Everyday UseMost current electronic devices now come with built-in rechargeable batteries.This is excellent, however, when the battery pack needs to be replaced, it becomes more difficult. This is a headache that may be easily avoided by using AAAA alkaline batteries, which are inexpensive and quick to replace.ConvenienceRemovable batteries offer an advantage over chargeable types in that they can be used in situations where energy is not accessible.If you're out camping and your torch runs out of juice, a quick battery replacement will have you back up and running in no time.Because rechargeable battery choices for many products are still unavailable, the AAAA battery remains relevant and handy in everyday life.AvailabilityAAAA batteries may be more difficult to locate because they are utilized in specialized applications, but they are still generally available both online and offline.Because of our extensive range of powerful batteries, we are Australia's leading provider of high-quality replaceable cells.3.3 AAAA Batteries are Environmentally FriendlyMercury, a heavy element known to harm the environment, is no longer present in modern AAAA dry cells.The packing is done with care, using biodegradable cardboard and as little plastic as possible. This is following consumer product environmental safety norms.When delivered, the safe and environmentally friendly blister pack retains the cells in place and prevents any inappropriate contact.The batteries also come in high number packs that are both cost-effective and environmentally friendly.Consumers are recommended to properly dispose of batteries to avoid undue pollution of land or water resources.The mercury-free cells also contain recyclable ingredients that may be used to make new battery components.  3.4 They Have a Durable, Heavy-Duty Structure  Quadruple-A cells are designed to survive harsh environmental conditions. For example, the average battery cell can endure temperatures ranging from -18 C to 55 C.The batteries' outside casings are constructed with a unique coating that reduces contact resistance for increased reliability. The sturdy design allows them to operate in a variety of situations and power specialty devices adequately, even under harsh conditions.This implies that whether you live in a tropical or frigid climate, you will always have optimal performance.Good quality batteries have a long shelf life and can be stored for up to 7 years without losing capacity.The manufacturers' quality assurance ensures efficient energy output throughout the battery's lifespan.Ⅳ The Best 4 Types of the AAAA Battery for You to Choose If you've ever used a little electronic device, such as a laser pointer, an electronic stylus, or a glucose meter, you've probably benefited from the power of the AAAA battery. However, replacing these batteries is not always simple because they are far more difficult to come by than other, more common ones. We created this list to make your search for AAAA batteries easier by highlighting the top ones on the market right now.3.1 What to Look for in AAAA BatteriesThe battery life will be critical. Another crucial factor to consider is shelf life, especially if you intend to buy extra batteries to store for later use. Battery purchases can add up over time, so consider using rechargeable AAAA batteries as a cost-saving option, especially if you don't mind their shorter battery life per charge.3.2 Best Overall: Energizer AAAA Alkaline BatteriesThese Energizer AAAA Alkaline Batteries have the longest battery life and are the most trustworthy AAAA batteries available. They're suitable for smart pens and other small electronics that require a consistent voltage output for long-term functionality. They also have a longer shelf life than most budget AAAA battery options, making them an excellent choice if you intend to store batteries for future use.3.3 Best Value: AAAA High-Performance Alkaline BatteriesAAAA High-Performance Alkaline Batteries provide 1.45 volts of dependable, long-lasting power and have a 3-year shelf life. These batteries are available in four- or eight-packs and are superior to other inexpensive AAAA battery options, even giving top-tier AAAA battery supplies a run for their money. They are also leak-proof and carefully sealed for further security.3.4 Best Rechargeable: EBL Individual Smart Battery Charger with 4 Pack AAAA Rechargeable BatteriesThe EBL Individual Smart Battery Charger with 4 AAAA Rechargeable Batteries is a terrific alternative for individuals looking for quality AAAA rechargeable batteries and a versatile charger to keep them operational. When compared to other rechargeable manufacturers, the 400-mAh AAAA batteries may be recharged over 1,000 times. The charger is also compatible with AA and AAA rechargeable batteries and includes several useful safety measures.3.5 Streamlight Stylus AAAA Replacement BatteriesThe Streamlight Stylus AAAA Replacement Batteries are an excellent choice for people looking for AAAA batteries to power an electronic stylus or penlight. These batteries last a long time and are dependable, especially given their low price. These batteries are particularly ideal for cameras and medical devices, and they work well in cold climates.Ⅴ An AAAA battery can't Replace 2 AA batteriesIt's a bit foolish to think that AAAA batteries are equivalent to two AA batteries in any way. The inverse is true.AAAA batteries have the same voltage as AA batteries but only about half the energy. When you connect two AA batteries in series, you obtain 3V, which a single AAAA battery can not provide. They will not be able to share the same placeThe battery size is not proportional to the letter identification. An AA battery is, in reality, significantly larger than an AAAA battery. Even if you had a couple of 1/2 AA batteries (fractional sizes exist for commercial and rechargeable batteries, but not for Wal-Mart batteries), you couldn't use them in place of an AA battery. To fit in an AA socket, two 1/2AA cells would have to be stacked end-to-end in series. That would add the voltages together, giving you a 3V battery instead of the predicted 1.5V battery.IEC and ANSI standards specify battery sizes, however many began as proprietary sizes and were given a letter designation when approved as a standard. The AAA, for example, was introduced in 1917 but did not become a standard until the 1960s. Most common batteries are also known by other names; for example, before 1980, the AAA was known as the U16 cell in the United Kingdom.Ⅵ FAQ1. What is the AAAA Battery Equivalent?Batteries of the same size and capacity as AAAA are referred to in a few different ways depending on the manufacturer. E96, LR8D425, MN2500, and MX2500 are direct replacements for AAAA. The only difference between these batteries and AAAA batteries is their nomenclature.Several batteries are the same size and dimensions as the AAAA battery, but they are not perfect counterparts or direct replacements because they are made of different chemistries that offer varied performances for different applications.Examples include lithium and other rechargeable types. Although these batteries have the same size as an AAAA battery, the differing chemistry allows for variable drain performance, allowing the battery to run for extended periods in low-use applications such as a wall panel. These batteries may not work in all applications that require an AAAA battery.Always reference the owner's handbook of your device to discover the exact battery that is needed for the best results.2. Where to Buy AAAA Batteries?AAAA batteries are very common and well-liked. This implies that a large range of manufacturers produces these batteries, and a wide range of shops sell them. It is critical to remember that not all AAAA batteries are made equal, nor do all sellers have the same commitment to quality. To avoid low-quality or worse, counterfeit batteries, only get your batteries from a highly reputable merchant who sells only the highest-quality brands.3. What is the AAAA Battery Used for?AAAA batteries are mostly used in small specialty devices such as glucose meters, laser pointers, compact headphone amplifiers, computer styluses, and a variety of other small-factor gadgets. 4. What are the Differences Between AAAA and AAA Batteries?Despite having a comparable physical architecture, an AAAA battery is approximately 40% less in weight and thickness than a AAA cell.In addition, quadruple-A batteries are utilized in tiny specialized gadgets such as styluses and glucometers, as opposed to AAA batteries, which are used in common devices such as remote controls and toys.It is important to note that, despite their similarities, these two battery types are not interchangeable. 5. Are A23 and AAAA Batteries the Same?These are two distinct types of batteries. See the table below for the key distinctions:Battery TypeOther NamesVoltageDimensionsCommon UsesAAAALR61R8D4251.5 V–3.7 VLength—42.5mmDiameter— 8.33mmPowered computer styluses, glucometers, laser pointers, LED penlightsA23LRV08GP23A23AEMN211.25V1.5VLength—28.5mmDiameter— 10.33mmBluetooth headsets, garage door openers, keyless car entry systems, home security systems6. Are E96 batteries AAAA?Energizer E96 Batteries are constructed with Energizer Power Seal Technology to provide longer-lasting performance than ordinary alkaline batteries. These AAAA batteries are a substitute for the LR8D425, MN2500, and MX2500.7. Can I Use AAA Battery Instead of AAAA?AAAA is the next size down from AAA. They cannot be used interchangeably.8. Where Can I Buy AAAA Batteries?They are available in convenience stores and supermarkets, although due to their specialized nature, availability is not always guaranteed. You may also buy them online from places like Battery Specialists.9. How Much does the AAAA Battery Cost?An alkaline twin pack costs $7.95 to $9.85, while single rechargeable 300mAh NiMH batteries start at $6.45. Prices may differ from one location to the next.10. How Long can AAAA Batteries Last When Unused? Most alkaline batteries should be able to survive between 5 and 10 years in their original packaging and still function properly.However, it is best to keep them in a cool, dry place away from excessive moisture, heat, or potentially dangerous corrosive substances.11. Are the 18650 and AAAABatteries the Same thing?No, there are two kinds. 18650 is similar to an elongated AA. AAAA is an elongated AAA with the number 041660 that has the same transactions.An AAAA battery has a maximum voltage of 1.5 volts, whereas a 18650 battery has a nominal voltage of 3.7 volts (mid-range) and can reach 4.2 volts. An AAAA battery measures 8.3 x 42.5mm, while 18650 measures 18 x 65mm. The AAAA battery is not usually rechargeable, but the 18650 is designed to be charged/discharged continuously at its nominal voltage. The AAAA battery has a capacity of 635 mah, while the 18650 battery has a capacity ranging from 1000 to 3500 mah. The AAAA battery is intended for laser pointers or other devices with low current demand. The 18650 is intended for usage in circumstances requiring a large draw. The AAAA is an alkaline battery, whereas the 18650 is a lithium battery.12. What are the Best Rechargeable AAAA Batteries?Is your "best" a consideration of worth, or is it a "who cares about money?"My practice emphasizes obtaining the best value while balancing price and capability. I try to buy generic house-brand batteries instead of expensive OEMs like Duracell or Energizer.13. How to Install the AAAA Battery in Your Device?Determine the positive and negative ends of the battery first. The flat side (sometimes with markings) of a common Alkaline AAAA battery is normally the positive side. A little round protrusion should be evident on the opposite side. Typically, the side is the negative end. You can easily align the positive and negative ends of the battery with the relevant markings on your device now that you've determined the positive and negative ends of the battery. Please keep in mind that certain gadgets feature small metallic tabs to help with battery retention and function. These tabs must remain unharmed and undamaged, as doing so may jeopardize the performance of your device.If you happen to move this tab slightly out of place, you can generally fix it by gently readjusting it back into the proper alignment.14. What is the Smallest Battery?The nano battery, at 150 nanometers across, is hundreds of times thinner than a human hair and more than 60,000 times smaller than a AAA battery. How many "A"s are there? Rice University invented the little battery, which is a hybrid of a battery and a supercapacitor.         

Introduction When the reverse bias voltage applied to the PN junction increases to a certain value, the phenomenon that the reverse current density suddenly begins to increase rapidly is called PN junction breakdown. From the mechanism, it can be divided into three categories: avalanche breakdown, tunnel breakdown and thermoelectric breakdown. Among them, there are two physical mechanisms for forming reverse breakdown in PN junction: zener breakdown and avalanche breakdown. Generally, both breakdowns coexist. So what is the difference between them? Avalanche Breakdown and Zener Breakdown Effect Explained Catalog Introduction Ⅰ Basic Characteristics 1.1 Avalanche Effect 1.2 Zener Effect Ⅱ Zener Effect vs Avalanche Effect Ⅲ Transistor Secondary Breakdown and Protection 3.1 A Brief Description 3.2 Cause of Breakdown 3.3 Precaution 3.4 Snubber Circuit Examples Ⅳ FAQ Ⅰ Basic Characteristics 1.1 Avalanche Effect As the reverse voltage increases, the electric field in the space charge region strengthens, and the energy obtained by the carriers in the barrier region also increases. When the reverse voltage is close to the breakdown voltage, these carriers with higher energy meet the neutral atoms in the space charge region and cause collision ionization, generating new electron-hole pairs. These newly generated electrons and holes will regain energy under the action of the electric field, collide with other neutral atoms to ionize them, and generate more electron-hole pairs. With reaction continues, causing the number of carriers in the space charge region to increase sharply, just like an avalanche, what’s more, the reverse current also increase sharply, resulting in breakdown. So this breakdown is called avalanche breakdown (or avalanche effect).This breakdown generally occurs in PN junctions with lower doping concentration and higher applied voltage. Because a PN junction in this state has a wider space charge region and more opportunities for impact ionization. Figure 1. Zener Breakdown vs Avalanche Breakdown 1.2 Zener Effect When the reverse voltage increases to a certain value, a strong electric field can be established in the barrier region, which can directly pull out the valence electrons bound in the covalent bond, so that a large number of electron-holes are generated in the barrier region. Then a large reverse current is formed, resulting in breakdown. At this time, atoms in the barrier region are directly excited under the action of a strong electric field is called Zener effect/breakdown. It is caused by the tunneling effect in quantum mechanics. Giving a simple metaphor, the simple understanding is that the two lines are too close, and they pass through directly. At this time, the potential barrier loses its function of blocking electrons, and a breakdown occurs.Zener breakdown generally occurs in PN junctions with higher doping concentrations. This is because the PN junction under this situation has a large charge density and a narrow width in the space charge region. As the temperature increases, the energy gap decreases, and a breakdown can be resulted in with a small reverse voltage. Figure 2. PN Junction Ⅱ Zener Effect vs Avalanche Effect 1) Zener effect mainly depends on the maximum electric field in the space charge region, and in the collision ionization mechanism is related to both the field strength and the collision accumulation process of carriers. Obviously, the wider the space charge region, the more times of multiplication, so the avalanche breakdown is not only related to the electric field, but also related to the width of the space charge region, which requires the thickness of the PN junction.2) Because avalanche breakdown is the result of impact ionization. If we increase the electrons and holes in the space charge region by means of illumination or fast particle bombardment, they will also have a multiplier effect. However, the above external effects will not have a significant impact on the Zener breakdown.3) The breakdown voltage is determined by the tunnel effect, and its temperature coefficient is negative, that is, the breakdown voltage decreases with the increase of temperature, which is the result of the decrease of the forbidden band width with the increase of temperature. The breakdown voltage determined by avalanche multiplication decreases with the increase of temperature due to the impact ionization rate (the ionization rate represents the number of electron-hole pairs generated by a carrier drifting a unit distance under the action of an electric field), and its temperature coefficient is positive. That is, the breakdown voltage increases with temperature. Zener with voltage lower than 5-6V is mainly due to Zener breakdown; Zener with voltage higher than 5-6V is mainly due to avalanche breakdown. Zener diodes with a voltage between 5-6V have similar breakdown degrees and the best temperature coefficient, which is why many circuits use 5-6V Zener tubes. The principle of the Zener tube determines that its response speed is not very fast, so a tube reference voltage is used in occasions with high speed requirements.4) For the PN junction with higher doping concentration and thinner barrier, it is mainly Zener breakdown. The PN junction with lower doping and therefore wider potential barrier is mainly avalanche breakdown, and the breakdown voltage is relatively high.The PN junction breakdown is an important electrical property, and the breakdown voltage limits the working voltage of the circuit, so semiconductor devices have certain requirements for the breakdown voltage. However, a variety of devices such as Zener diodes, avalanche diodes, and tunnel diodes can be fabricated by using the breakdown phenomenon.Under normal circumstances, the avalanche breakdown and Zener breakdown are within a certain range of conditions (breakdown voltage, time), with the normal working conditions are restored, are reversible. If it is only for protection, the TVS voltage regulator tube is mainly used for voltage regulation. The smaller the current passing through, the better. When the instantaneous voltage exceeds the normal working voltage of the circuit, the TVS diode will avalanche, providing an ultra-low resistance path for the instantaneous current, which is diverted through the diode, avoiding the protected device. In additional, the protected circuit keeps the cut-off voltage until the voltage returns to normal value. When the instantaneous pulse ends, the TVS diode automatically returns to the high resistance state, and the entire circuit entering the normal voltage, the failure mode of the TVS tube is mainly short circuit. But when the overcurrent passed is too large, it may also cause the TVS tube to be burst and open. Figure 3. TVS Diode Ⅲ Transistor Secondary Breakdown and Protection 3.1 A Brief Description In most switching power supplies, power switching transistors work under high-voltage, high-current high-frequency pulses, and switching on and off under such conditions will cause a great impact on the transistors. Secondary breakdown is one of the important causes of transistor damage. To design a high-performance, high-reliability switching power supply, it is necessary to have a clear understanding of the secondary breakdown of transistors and avoidance measures. 3.2 Cause of Breakdown The secondary breakdown is mainly caused by the high local temperature in the device body. The temperature rise is caused by thermal imbalance when forward biased and avalanche breakdown when reverse biased.Because the thermal resistance of the transistor is unevenly distributed throughout the tube, in some weak areas, the temperature rise will be higher than other parts, forming a so-called "hot spot", and so on until a critical temperature, causing the breakdown of the tube. The secondary breakdown caused by the avalanche breakdown is a phenomenon in which the electric field distribution of the junction is changed due to the excessive current density at some points after the primary avalanche breakdown occurs, resulting in a negative resistance effect and the local temperature is too high. 3.3 Precaution Turn-on and turn-off losses are important factors that affect the normal operation of switching devices. In particular, the transistor is prone to secondary breakdown in the dynamic process, and this phenomenon is directly related to the switching loss. Therefore, reducing the switching loss of the self-shutdown device is a necessary measure for the correct use of the device. There are two ways to reduce losses:(1) Turn off the transistor at the lowest possible collector-emitter voltage (Vce).(2) When the transistor is turned off during the rise of the emitter voltage, the emitter current should be minimized. For example, introducing a buffer circuit is one of the ways to achieve the above purpose. 3.4 Snubber Circuit Examples The following snubber circuits can be used in the design of switching power supplies to ensure that the transistors operate within a safe area.1) The commonly one is an energy-consuming shutdown snubber circuit. Although it consumes more energy, this circuit is simple. Figure 4. Commonly Used Shutdown Snubber Circuit It consists of an RCD network connected in parallel with transistor switches. When the transistor is turned off, the load current charges the capacitor C through the diode D, so that the collector current of the tube gradually decreases. Because the voltage across the capacitor C cannot be abruptly changed, its collector voltage is restrained. The situation where the collector voltage and current reach their maximum values at the same time is avoided, so there is no maximum instantaneous power consumption spike. When the tube is turned on, the capacitor releases energy and dissipates it in the resistor.2) Two commonly used energy-consuming turn-on snubber circuits.a. An inductor-diode network is connected in series with the transistor collector to form a turn-on snubber circuit. When the tube is turned on, the inductance Ls controls the current rise rate di/dt during the collector voltage drop. When the tube is turned off, the energy stored in the inductor Ls 1/2 freewheels through the diode Ds, and its energy is dissipated in the resistance of Ds and the reactor. Figure 5. Open Snubber Loop with Unsaturated Reactance b. Turn-on snubber circuit with saturable reactor: The purpose of using turn-on snubber circuit is to make the collector voltage drop to 0 when the collector current of the transistor is small, so as to minimize the turn-on loss. Especially for inductive loads, the effect is more significant. The designed saturable reactor should be: in one hand, after the collector voltage drops to zero, the buffer reactor is in a saturated state; in the other hand, before saturation, the collector voltage drops to zero, the reactor presents a high resistance, and the magnetizing current flowing through the tube is small to achieve the purpose of reducing turn-on loss. Figure 6. Open Snubber Circuit with Saturable Reactance 3) In the figure, Co is a transfer capacitor, and Dc is a feedback diode. These two components feed back energy to the load. When the tube is turned off, the buffer capacitor Cs is charged to the power supply voltage Vcc, and when the tube is turned on next time, the load current is transferred from the freewheeling diode Df to the transistor. At the same time, the voltage on Cs resonates to Co. When the tube is turned off again, the Cs is charged again, the capacitor Co is discharged to the load, and the energy is fed back. Figure 7. Passive Feedback Shutdown Buffer Circuit 4) This circuit stores the magnetic field energy and feeds back to the power supply through the transformer. The transformer is wound with two wires, and its primary side has a certain inductance; the polarity of the width side is opposite to that of the primary side, and a reverse diode is connected. When the tube is turned on, the primary side bears all the power supply voltage, and the secondary side has no energized circuit. When the tube is turned off, the polarity of the induced voltage on the secondary side is reversed, and when its voltage is higher than the power supply voltage Vcc, energy is fed to the power supply. Figure 8. Passive Feedback Opens the Buffer Circuit 5) The turn-on snubber circuit and the turn-off snubber circuit are combined to form a composite snubber circuit, and the composite snubber circuit has a protective effect when the transistor is turned on and off. This kind of circuit is also divided into two types: energy consumption and energy feeding.a. When the tube is turned on, the snubber capacitor is discharged through the Cs, Rs, and Ls loops, which reduces the current rising rate that the tube bears. In addition, when the tube is turned on, the inductance Ls can also limit the reverse recovery current of the freewheeling diode Df. Figure 9. Energy-consuming Composite Buffer Circuit b. When the transistor is turned off, the capacitor Co and the inductor Ls operate in parallel to feed the stored energy to the load. When the capacitor Co is discharged, the voltage on the inductor Ls gradually decreases to 0, and the load current is conducted through the freewheeling diode Df during this period. Figure 10. Energy-feeding Compound Snubber Circuit The various snubber circuits mentioned above can be divided into two types, namely energy-consuming and energy-feeding. The energy-consuming circuit is simple but relatively consumes more energy, and is suitable for the use of low-power circuits. The energy-feeding circuit is complex, but in a high-power supply, if the energy dissipated by the snubber circuit is dissipated in the form of heat, it is bound to cause a lot of trouble, so the energy-feeding buffer circuit should be used.   Ⅳ FAQ 1. What is a zener breakdown voltage?A normal p-n junction diode allows electric current only in forward biased condition. ... This sudden rise in electric current causes a junction breakdown called zener or avalanche breakdown. The voltage at which zener breakdown occurs is called zener voltage and the sudden increase in current is called zener current. 2. Which breakdown occurs in Zener diode?avalanche breakdownIn Zener diodes, avalanche breakdown occurs. When the Vz is greater than 8 volts in a Zener diode, avalanche breakdown occurs because there is an isolation of electrons and holes. 3. What is difference between avalanche and zener breakdown?The main difference between Zener breakdown and avalanche breakdown is their mechanism of occurrence. Zener breakdown occurs because of the high electric field whereas, the avalanche breakdown occurs because of the collision of free electrons with atoms. Both these breakdowns can occur simultaneously. 4. How do you calculate Zener breakdown voltage?The reverse current that results after the breakdown, is called Zener current (Iz). At breakdown, increase of VI increases II by large amount, so that V0 = VI– RI II becomes constant. This constant value of V0 which is the reverse breakdown voltage, is called Zener voltage. 5. What is avalanche breakdown of diode?What is Avalanche Breakdown? The avalanche breakdown occurs when a high reverse voltage is applied across the diode. As we increase the applied reverse voltage, the electric field across the junction increases. This electric field exerts a force on the electrons at the junction and frees them from covalent bonds. 6. How does an avalanche breakdown take place?Avalanche breakdown usually occurs when a high reverse voltage is applied across the diode. So as we increase the applied reverse voltage, the electric field across the junction will keep increasing. This generated electric field exerts a force on the electrons at the junction and it frees them from covalent bonds. 7. What is avalanche effect of Zener diode?Avalanche breakdown involves minority carrier electrons in the transition region being accelerated, by the electric field, to energies sufficient for freeing electron-hole pairs via collisions with bound electrons. The Zener and the avalanche effect may occur simultaneously or independently of one another. 8. What do you mean by zener breakdown voltage?When reverse biased voltage applied to the zener diode reaches zener voltage, it starts allowing large amount of electric current. At this point, a small increase in reverse voltage will rapidly increases the electric current. Because of this sudden rise in electric current, breakdown occurs called zener breakdown. 9. Is Zener voltage the same as breakdown voltage?The breakdown voltage,commonly called the Zener voltage, is the reverse-biased voltage that causes the diode to conduct current. Breakdown voltages usually range from 2.4 V to hundreds of volts. 10. What is meant by Zener effect?The Zener effect is a type of electrical breakdown that occurs in a reverse-biased PN junction when the electric field enables tunnelling of electrons from the valence to the conduction band of a semiconductor, leading to a large number of free minority carriers which suddenly increase the reverse current. 11. Which factor is responsible for Zener effect?In effect, electrons from the p-side valence band are able to tunnel across the barrier into the empty states in the n-side conduction band when a small reverse bias is applied. The result is a strong current from n to p in the diode, causing zener breakdown. 12. What is valence breakdown?Avalanche breakdown (or “the avalanche effect”) is a phenomenon that can occur in both insulating and semiconducting materials. It is a form of electric current multiplication that can allow very large currents within materials which are otherwise good insulators. It is a type of electron avalanche.

CatalogIntroductionⅠ CR123A Battery Basics    1.1 What is a CR2 Battery?    1.2 CR2 Battery Features and SpecificationsⅡ CR2 Lithium Battery Replacement    2.1 CR2 Batteries Cross Reference Chart    2.2 CR2 Battery Chemistry    2.3 Rechargeable CR2 Battery Replacement    2.4 15270 ChemistriesⅢ 11 Safety Precautions to Take While Using the CR2 Battery?Ⅳ Best CR2 Battery For Everyday ElectronicsⅤ FAQ    5.1  Are CR2 Batteries Rechargeable?    5.2  How Long does the CR2 Battery Last?    5.3 What Battery is Equivalent to the CR2 Battery?    5.4 Are CR2 Batteries the Same as CR123A?    5.5 Are C2 and CR2 Batteries the Same?    5.6 What Uses the CR2 Battery?    5.7 Where to Buy the CR2 Battery?    5.8 Is the Energizer 123 the Same as CR2?    5.9 What Warnings Should I Consider While Using Lithium Batteries Such As Lithium-Ion 15270?IntroductionThe CR2 battery, which is found in cameras,weapon-mounted lights, golf rangefinders, EDC flashlights, and security devices, is revered around the world. A standard cylindrical lithium battery is referred to as a CR2. This is the type of battery used in cameras (such as the CR2). This is due to their small size, which makes them ideal for electronic devices on the go. A CR2 lithium battery's shelf life is determined by its model and manufacturer. The Energizer brand, for example, puts more strain on its batteries than other brands, ensuring comparative endurance under extreme conditions.Ⅰ CR2 Battery Basics1.1 What is a CR2 Battery? CR2 battery and Pad replacementThe CR2 battery is a cylindrical lithium cell with measurements of 27mm x 15.6mm. In simple terms, the CR2 battery resembles a smaller version of a D Cell Battery, or, to put it another way, a can. These batteries can be used in a wide range of situations. They're commonly found in cameras that require a high-capacity lithium battery, as well as in a variety of industrial applications. Because of its numerous applications, this battery is extremely popular and, as a result, can be difficult to locate. Panasonic, Duracell, and Energizer are just a few of the big and small brands that make them. This article will provide you with all of the information you need to know about the CR2 battery.CR2 lithium battery1.2 CR2 Battery Features and SpecificationsThe CR2 battery has a nominal voltage of 3.0 volts and a cutoff voltage of 2.0 volts. It is a non-rechargeable lithium battery.The CR2 battery has a diameter of 15.6 mm and a height of 27 mm (1.063 inches). The CR2 battery typically has a capacity of 800 to 850 mAh, though this varies depending on the device's cutoff voltage and drain conditions (current strength, temperature, and similar).Many manufacturers use the standard CR2 label but add a letter or two to emphasize the brand, for example, when labeling their batteries.The 1CR2, DL-CR2, DLCR2, 5046LC, CR15H270, EL1CR2, KCR2, and other CR2 battery equivalents are commonly used.Manganese-dioxide lithium 15.6 x 27 mm non-rechargeable cylindrical batteries are the most common, with carbon-monofluoride lithium 15.6 x 27 mm non-rechargeable cylindrical batteries ('BR2 battery') being extremely rare.The shelf life of CR2 batteries varies depending on the model and brand, but it is typically 3+ years, with some brands having 10+ year shelf lives, making them ideal for standby or emergency devices (panic lights, EDC flashlights, medical equipment, etc.).CR2 batteries are fairly common, and most reputable brands offer them, so finding good ones from online shops and stores should not be a problem.CR2 Battery Nominal Voltage:3 VoltsCR2 Capacity (Lithium)≈  800 mAhCR2 Operating Temperature:-40°C – 60°C CR2 Height:27.0 mmCR2 Width (Diameter):15.60  mmCR2 Chemistry:Lithium Manganese Dioxide (Li/MnO2                                                  Technical Specifications Of The CR2 BatteryⅡ CR2 Lithium Battery Replacement2.1 CR2 Batteries Cross Reference ChartThe table below compares and contrasts the most important characteristics of several popular CR2 battery models.A nominal voltage of 3.0 volts, a cutoff voltage of 2.0 volts, and a very low self-discharge rate are all included in the chart.Also, while the 'official' operating temperature range is usually between -40°C and +70°C, it is important to remember that the performance of these batteries is temperature-dependent, and they perform best at room temperatures (20-25°C), with temperatures between -10°C and 50°C being avoided if at all possible.BatteryCapacityDischarge CurrentsDatasheetEnergizer CR2800 mAh, 100Ω @21°C down to 2.0V1000 mA max. continuous1200 mA, 3s/7s, @21°C, 760 cycles, down to 1.8V1800 mA, 3s/7s, @21°C, 400 cycles, down to 1.8V2500 mA max. pulseEnergizer CR2GP CR2800 mAh, @10 mA @23°C down to 1.8V10 mA continuous900 mA, 3s/27s, @23°C, 900 cycles, down to 1.6VGP CR2Panasonic CR2850 mAh20 mA continuous900 mA, 3s/27s, @20°C, 1000 cycles, down to 1.8VPanasonic CR2Varta CR2850 mAh, @20mA @20°C down to 2.0V20 mA continuous900 mA, 3s/27s, @25°C, 900 cycles, down to 1.5VVarta CR2As can be seen, the CR2 battery can easily deliver continuous currents of 10-20 mA.They are, however, exceptional high-discharge performers, with the best models capable of 900-1000 cycles (3 seconds ON, 27 seconds OFF) at 1.5-1.8 volts at room temperature.Some manufacturers (such as Energizer in this chart) stress their batteries even more by testing them with 3s/7s cycles; even under such conditions, Energizer CR2 batteries have an actual capacity of 760 mAh (down to 1.8V), which is very similar to the nominal capacity of 800 mAh (down to 2.0V).CR2 batteries are commonly used in high-drain devices such as cameras, range finders, compact EDC flashlights, and similar devices due to their performance.2.2 CR2 Battery ChemistryThe 3v CR2 battery that measures 27mm in length and 15.6mm in width (diameter). Lithium, alkaline, and Li-Ion batteries are used in its technology. Due to the general manganese oxide in its positive electrode and the spiral nature of its polar plate, it has a very high discharge rate.A Positive Temperature Coefficient (PTC) safety device is also built into the battery to limit current during short circuit conditions.Part NumberCR2Chemical SystemLithium / Manganese Dioxide (Li/MnO2)Typical Lithium content0.28 gramsNominal voltage (Open circuit voltage)3.0VTypical capacity800mAH (to 2.0volts, rated at 100 ohms at 21℃)Nominal capacity850mAHContinuous drain (standard discharge current)20mADimensions15.6 mm (max diameter) 27.0 mm (max height)Typical Weight11.0gTypical volume5.2 cm3Temperature rangeDischarge: -40℃ to 60℃ Storage: -40℃ to 75℃Maximum continuous discharge current1000 mA continuous (2500 mA pulse)Maximum reverse charge2 µA2.3 Rechargeable CR2 Battery ReplacementA few letters can be added to CR2 to emphasize the brand on the label in some cases. 1CR2, KCR2, DLCR2, and other equivalents are possible.The 15270 (or RCR2) is commonly referred to as the "rechargeable CR2." It's a rechargeable lithium-ion battery with a single prismatic cell and a one-parallel, one-series configuration.In comparison to primary CR2 models, it is slightly smaller (15 by 26.6mm). It can be charged multiple times without experiencing the "lazy battery effect."Other technical characteristics are:Voltage: 3.7V (nominal)Capacity nominal: 450 mAhStandard: 0.2C, continuous: 1C Constant discharge current0 to 45°C for charging; -20 to 60°C for dischargeApproximate cell weight: 20 g2.4 15270 ChemistriesThe most common chemistries are lithium manganese oxide (LiMn2O4) and lithium iron phosphate (LiFePO4).The battery on the 15270 is protected from overheating and overcharging by a built-in Battery Management System (BMS). As a result, a "protected" 15270 battery has a capacity of 400-600 mAh.The non-rechargeable CR2 and the 15270 are fully compatible thanks to a BMS that reduces the output voltage to 3.0V.Rechargeable 15270s have a reputation for lasting longer, providing better value for money, and outperforming their primary CR2 counterpart.Ⅲ 11 Safety Precautions to Take While Using the CR2 Battery?The CR2 battery is designed to be explosion-proof. However, due to the explosive nature of lithium metal and organic electrolytes within the product packaging, special instructions must be followed.1Do not light the batteries on fire. They are prone to catching fire.2Do not charge anything.3Avoid short-circuiting.4Do not attempt to disassemble.5Avoid exposing batteries to extreme temperatures, including direct sunlight. 30°C is the recommended storage temperature. Temperatures above 45°C should be avoided. Temperatures below -40°C also deform the plastic parts and may cause leakage.6Avoid storing the batteries in places with high humidity. To avoid self-discharge due to corrosion or a decrease in insulation, storage humidity should not exceed 70%.7KEEP BATTERIES OUT OF THE REACH OF CHILDREN. If a child swallows a battery, seek medical attention immediately.8Never mix old and new batteries or batteries from different series.9Do not use a wire to connect the negative and positive electrodes. Carry batteries separately from metallic objects such as necklaces, coins, and so on.10Never use an ultrasonic wave washer to clean the battery.11Always follow the instructions on the package for safe usage.Ⅳ Best CR2 Battery For Everyday ElectronicsThe Energizer CR2 lithium battery is ideal for use in commonplace electronics. It will always provide a consistent source of power to any device. The 800 mAh rating ensures that this battery can power a device for extended periods.These batteries are not only powerful but also very durable and have very long battery life. They also slowly discharge power to the device. Have the ability to retain power for up to ten years when stored. Perfect for cameras, CD players, and portable speakers.Ⅴ FAQ5.1 Are CR2 Batteries Rechargeable?Most CR2 batteries cannot be recharged, but some can. Typically, the label of a CR2 battery will indicate whether or not the battery is rechargeable. Rechargeable batteries are also referred to as "secondary batteries," whereas non-rechargeable or single-use CR2 batteries are referred to as "primary batteries." It is critical to determine whether a CR2 battery is a "primary battery" or a "secondary battery." Attempting to recharge a non-rechargeable battery (particularly a lithium battery) can result in a fire, explosion, or the destruction of your charger/device. Even when using a high-quality rechargeable battery, it is critical to use the proper charger to avoid problems. Using the wrong or incompatible charger for your CR2 battery can cause the battery to malfunction or stop working entirely.5.2 How Long does the CR2 Battery Last?The lifespan of a CR2 battery is heavily dependent on the battery's manufacturing quality and application. Assuming the battery is new and purchased from a reputable source, there is still a wide range of service life available depending on usage. A CR2 battery may last less than a month for a frequent application that requires a large amount of energy, such as a high lumen flashlight. With the right conditions, the service life of a more passive application, such as a home security alarm panel, can be over a year. Essentially, how long your CR2 battery will last is determined by what you require it to do.5.3 What Battery Is Equivalent to the CR2 Battery?DLCR2, KCR2, ECR2 1CR2, and 5046LC could be direct replacements and equivalents for the CR2 battery. All of these batteries are direct replacements for the CR2 battery and are classified as primary or non-rechargeable batteries. The 15270 and 15266 batteries are rechargeable or secondary versions of the CR2. These rechargeable CR2 batteries have a slightly lower capacity (lower mAh) than non-rechargeable versions, but they will still fit in and power the same devices. The non-rechargeable version has a longer single-use life, but the rechargeable CR2 battery saves you money over time.5.4 Are CR2 Batteries the Same as CR123A?The CR2 battery is not interchangeable with the CR123A battery. Because the CR2 battery is slightly shorter than the CR123A battery, it will not fit in the majority of applications that require a CR123A battery. Furthermore, the CR123A battery will deliver approximately 50% more output than the CR2 battery, implying that even if you were able to seat a CR2 battery into a CR123A device, it would not be able to deliver the full power required, and your device would either function poorly or not at all. These batteries do have some similarities, such as the fact that they are both made of lithium manganese dioxide and are both 3-volt batteries.5.5 Are C2 and CR2 Batteries the same?The CR2 battery is not commonly referred to as a C2, but some small manufacturers do sell batteries labeled C2 that are identical to the CR2. The CR2 battery is typically designated by the majority of major manufacturers. In addition, certain retail packaging for C cell batteries may cause some confusion. Some retail packs of two C batteries may have C 2 written on the top of the packaging. This does not imply that it is the same as a C2 (CR2) battery, but rather that there are two C cell batteries in the pack.5.6 What Uses the CR2 Battery?Military, industrial, medical, and consumer applications are all possible with the CR2 battery. The CR2 battery is used in weapon lights,  laser designators, optics, laser rangefinders, and communications devices in the military. Alarm batteries and power for various instruments are medical applications for the CR2 battery. Lights, alarms, cameras, and memory backup applications are just a few examples of industrial and consumer uses.5.7 Where to buy the CR2 Battery?CR2 batteries are extremely popular and common. This means that these batteries are made by a wide range of manufacturers and sold by a wide range of retailers. It is important to remember that not all CR2 batteries are created equal, and not all retailers are equally committed to quality. To avoid low-quality or, worse, counterfeit batteries, it is critical to purchase your batteries from a highly reputable retailer that sells only the highest quality brands.5.8  Is the Energizer 123 the Same as CR2?No, it isn't.The Energizer 123 (or CR123) battery is 34.5mm long, while the CR2 is only 27mm long. As a result, even though both claim a voltage of 3V, the CR123 cannot be used in place of the CR2.5.9 What Warnings Should I Consider While Using Lithium Batteries Such As Lithium-Ion 15270?Before the first use, fully charge the battery.Charge the battery frequently and with high-quality chargers. When charging, Do not leave it unattended.Avoid storing your Li-ion battery fully charged for extended periods.Keep it cool and dry, away from heat.Insert a Li-ion battery gently. Use no force.    

Introduction to Amplifier GainSummary (2026 Update): From 5G RF front-ends to precision IoT sensors—Gain remains the fundamental metric of signal amplification. It quantifies the ratio of output to input for voltage, current, or power, typically expressed in decibels (dB). This guide covers the essential physics, calculation methods, and frequency response analysis required for high-performance circuit design in 2026.In electrical circuits, Gain generally refers to the degree of increase in current, voltage, or power of components, circuits, equipment, or systems. It is specified in decibels (dB), meaning the unit of gain is generally dB, which represents a relative value rather than an absolute unit like Volts or Amps. In short, its general meaning is the magnification factor. In electronics, it is strictly the ratio of the signal output to the signal input of a system. For example, antenna gain is a parameter that represents the radiation concentration of a directional antenna. But what exactly is amplifier gain in the context of modern semiconductors? How do you calculate it using 2026 industry standards? Read the following technical notes for a deep dive.Ⅰ Amplifier Gain Fundamentals1.1 Definition and ContextAmplifier gain is the logarithm of the ratio of output power to input power, used to express the magnitude of power amplification. It also refers to the magnification of voltage or current. The decibel (dB) is the standard unit. The total magnification of an electronic system is often several thousand (e.g., Low Noise Amplifiers) to millions (e.g., Operational Amplifiers). For example, a modern digital radio receiver might need to amplify a signal 20,000 times or more from the antenna to the DSP or speaker. Using linear numbers makes calculations unwieldy. In decibels, we take a logarithm, making the numbers manageable. Crucially, when amplifiers are cascaded (connected in series), the total linear magnification is multiplied, but the total gain in dB is additive, simplifying system design.1.2 Gain Representation in Decibels (dB)Voltage gain Av(dB) = 20log(|Av|)The voltage gain in decibels is 20 times the base-10 logarithm of the voltage ratio (Output Voltage / Input Voltage).Current gain Ai(dB) = 20log(|Ai|)The current gain in decibels is 20 times the base-10 logarithm of the current ratio.Power gain Ap(dB) = 10log(Ap). Note the factor is 10, not 20. Power gain = Output Power / Input Power.Why use decibels? Beyond simple convenience, human perception (like hearing) is logarithmic. A gain of 100,000,000 times (linear) is awkward to document. Converted to dB, it becomes 160dB, which is standard engineering notation. This principle mirrors why computing uses binary or hexadecimal. Engineers can easily convert between linear magnification and decibels depending on the simulation or datasheet requirement.Ⅱ Types of Amplifier Gain2.1 Voltage Gain (Av)Av = Vo / Vi means that voltage gain equals the amplifier's output voltage divided by the input voltage. This is the primary metric for Voltage Amplifiers.🔺 Open Loop Voltage Gain (AVOL)In the absence of negative feedback, the amplification factor of an operational amplifier (Op-Amp) is called Open-Loop Gain. Ideally, this is infinite. In practice, modern precision Op-Amps (like the OPA series replacing legacy chips) feature gains between $10^5$ to $10^7$. Representations include dB (e.g., 106dB) or V/mV. While legacy chips like the μA741C or LM318 had typical values around 200V/mV, 2026-era rail-to-rail amplifiers offer significantly higher linearity. We use the "virtual ground" assumption in calculations because the immense AVOL forces the differential input voltage to near zero.The Ideal Op Amp Characteristics:1) Open loop gain is infinite.2) Input impedance is infinite (no loading effect), and output impedance is 0.3) Bandwidth is infinite (instantaneous response).Video: How To Calculate the Voltage Gain of a Transistor Amplifier🔺 Closed Loop Voltage GainThis refers to the gain of the entire circuit after a negative feedback loop is applied. Feedback stabilizes the gain and widens bandwidth. The formula is: voltage gain = 20log(Vo / Vi).🔺 IF (Intermediate Frequency) Voltage GainThe IF voltage gain (Avm) refers to the maximum voltage gain within the passband—specifically the frequency range where the voltage amplitude remains above 0.707 of the maximum (the -3dB points).2.2 Current Gain (Ai)Ai = Io / Ii defines current gain as the output current divided by the input current. These circuits are known as Current Amplifiers (or Current Mirrors in IC design).2.3 Transimpedance Gain (Rm)Ar = Vo / Ii. Here, the gain represents Output Voltage / Input Current. This topology is called a Transimpedance Amplifier (TIA), critical in 2026 for photodiode sensors and fiber optic receivers.2.4 Transconductance Gain (gm)A = Io / Vi. Transconductance gain is the ratio of Output Current to Input Voltage. These are Transconductance Amplifiers (OTAs), often used as the input stage in modern Op-Amps. Ⅲ Fully Differential Amplifier GainA fully differential amplifier (FDA) is standard in modern high-speed ADC drivers. It features four distinct gain metrics based on Common Mode (CM) and Differential Mode (DM) signals.Adm (Differential Gain): The gain from differential input to differential output. This is the desired signal amplification.Acm (Common Mode Gain): The gain from common-mode input to common-mode output. Ideally, this should be zero to reject noise.Adcm (Mode Conversion - Diff to CM): Gain from differential input to common-mode output.Acdm (Mode Conversion - CM to Diff): Gain from common-mode input to differential output.Design Goal: Maximize Adm while minimizing Acm, Adcm, and Acdm. A high Adm ensures strong signal integrity. A low Acm is crucial; if Acm is non-zero in cascaded stages, common-mode noise (like 60Hz hum or EMI) amplifies, causing "rail saturation." Adcm and Acdm must be minimized to prevent signal distortion and feedback loops that can destabilize the amplifier. In 2026 designs, Common-Mode Rejection Ratio (CMRR) is the key spec that aggregates these parameters. Ⅳ Frequency Response and Gain CalculationCapacitors in an amplifier circuit dictate the frequency response. We analyze gain across three bands: Low Frequency (LF), Intermediate Frequency (IF), and High Frequency (HF).Figure: The Relationship between Gain and Frequency (Bode Plot)1) Intermediate Frequency (IF):Coupling/Bypass Capacitors → Short Circuit.Transistor Parasitic Capacitance → Open Circuit.The gain expression is frequency-independent (flat). This is the nominal gain of the amplifier.2) Low Frequency (LF):Coupling and bypass capacitors are significant here. Their impedance rises as frequency drops, reducing gain. The circuit acts as a High-Pass Filter.3) High Frequency (HF):Internal transistor capacitances (Cpi, Cmu) and stray load capacitances dominate. As frequency rises, these act as short circuits, shunting the signal to ground. The circuit acts as a Low-Pass Filter.Gain Function and Corner Frequencies (S-Domain Analysis)In the complex frequency domain (s-domain), Capacitance = 1/sC and Inductance = sL. The system function A(s) is a ratio of polynomials:Factoring the numerator and denominator reveals the zeros and poles:Key Characteristics:1) For physical stability, the number of zeros (m) must be ≤ poles (n).2) In low-frequency amps, poles are real numbers corresponding to RC time constants.The gain function is split into three bands:Determining the Lower Corner Frequency (fL):At low frequencies, s → ∞ relative to the low poles. The response is governed by coupling capacitors. If one pole is significantly larger (closer to the passband) than the others, it is the Dominant Pole (p1).Approximation using the Dominant Pole concept:......(a)Determining the Upper Corner Frequency (fH):At high frequencies, transistor internal capacitances dominate. Here, we look for the smallest pole (closest to the passband) which acts as the dominant high-frequency pole.The simplified derivation for bandwidth (fBW) typically relies on identifying these dominant poles in the transfer function. Ⅴ FAQ: Common Questions on Amplifier Gain1. How is gain strictly defined in electronics?Gain is the dimensionless ratio of Output / Input. While it has no physical units (Volts/Volts cancel out), it is almost always expressed in Decibels (dB) to handle large magnitudes comfortably. The symbol is "A" (e.g., Av for Voltage Gain).2. What is the difference between Voltage, Current, and Power Gain?Voltage Gain (Av) is Vout/Vin. Current Gain (Ai) is Iout/Iin. Power Gain (Ap) is Pout/Pin. Note that Power Gain is the product of Voltage and Current Gain. In dB: Power Gain uses 10log, while Voltage/Current uses 20log.3. What is the typical current gain (Alpha) of a Common-Base amplifier?In a Common-Base (CB) configuration, the current gain is called Alpha (α). Since the emitter current is the sum of base and collector current (IE = IB + IC), and the output is taken from the collector, the output is always slightly less than the input. Thus, α is always < 1 (typically 0.95 to 0.99).4. How do you calculate the gain of a Differential Amplifier?For a standard differential amp with balanced resistors (R1=R2=R3=R4), it is a Unity Gain device where Vout = V2 - V1. If resistors differ, the gain is determined by the ratio of the feedback resistor to the input resistor.5. What defines an "Ideal" Op-Amp in 2026 theory?An ideal op-amp is a theoretical construct with: Infinite Open Loop Gain, Infinite Input Impedance (draws no current), Zero Output Impedance (drives any load), and Infinite Bandwidth. Real-world components strive to approach these limits using advanced CMOS or BiCMOS processes.6. Why is Op-Amp gain so high?Op-Amps are designed as multi-stage differential amplifiers. They utilize active loads (current mirrors) rather than passive resistors internally, allowing them to achieve massive Open Loop Gains (often >100,000x) to ensure precise performance when closed-loop feedback is applied.7. How do I find the gain of an Inverting Op-Amp?The formula is straightforward: Gain (Av) = - (Rf / Rin). Rf is the feedback resistor, and Rin is the input resistor. The negative sign indicates a 180-degree phase shift.{ "@context": "https://schema.org", "@type": "TechArticle", "headline": "Comprehensive Guide to Amplifier Gain: Formulas, Types, and Calculation (2026 Edition)", "description": "A deep dive into Amplifier Gain in electronics. Learn about Voltage, Current, and Power gain, decibel conversion, frequency response analysis, and modern fully differential amplifier theories.", "datePublished": "2019-01-01", "dateModified": "2026-01-05", "author": { "@type": "Organization", "name": "Kynix Semiconductor" }, "mainEntity": { "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "How is gain strictly defined in electronics?", "acceptedAnswer": { "@type": "Answer", "text": "Gain is the dimensionless ratio of Output divided by Input. While it has no physical units, it is almost always expressed in Decibels (dB). The symbol is usually A." } }, { "@type": "Question", "name": "What is the formula for Voltage Gain in dB?", "acceptedAnswer": { "@type": "Answer", "text": "Voltage Gain in dB is calculated as 20 * log10(Vout / Vin)." } }, { "@type": "Question", "name": "What is the difference between Voltage, Current, and Power Gain?", "acceptedAnswer": { "@type": "Answer", "text": "Voltage Gain (Av) is Vout/Vin. Current Gain (Ai) is Iout/Iin. Power Gain (Ap) is Pout/Pin. In dB conversion, Voltage and Current use 20log, while Power uses 10log." } }, { "@type": "Question", "name": "What is the current gain (Alpha) of a Common-Base amplifier?", "acceptedAnswer": { "@type": "Answer", "text": "In a Common-Base configuration, the current gain (Alpha) is always less than 1 (unity), typically between 0.95 and 0.99." } }, { "@type": "Question", "name": "How do you calculate the gain of an Inverting Op-Amp?", "acceptedAnswer": { "@type": "Answer", "text": "The gain is calculated using the formula: Gain = - (Rf / Rin), where Rf is the feedback resistor and Rin is the input resistor." } } ] }}

CatalogIntroductionⅠ CR123A Battery Basics    1.1 What is a CR123A Battery?    1.2 Maximum Capacity of the CR123A Battery    1.3 The Manner of Applications of the BatteriesⅡ CR123A Battery Specifications    2.1 Technical Specifications of the CR123A Battery    2.2 Non-Rechargeable CR123A Battery Specifications    2.3 Rechargeable CR123A Battery SpecificationsⅢ Top 4 Considerations to Choose the CR123A Lithium BatteryⅣ Choosing the Best CR123A BatteriesⅤ Shopping for CR123A BatteriesⅥ Why Use CR123A Batteries for Arlo Cameras    6.1 Higher Voltage    6.2 No Voltage Drops    6.3 Lighter Weight    6.4 Longer Battery LifeⅦ FAQ    1. Why is it Called a CR123A?    2. Are there Rechargeable CR123A Batteries?    3. Can I Use 2 x CR123A Batteries Instead of an 18650 Battery?    4. Why do I See Names like EL123A, 123A, and K123LA?    5. Are all CR123A Batteries the Same?    6. How Long does a CR123A Battery Last?    7. What Battery is Equivalent to the CR123A Battery?    8. Are CR2 Batteries the Same As CR123A?    9. Where to Buy CR123A Batteries?    10. Are CR123A and CR123 Batteries the Same?    11. Can you Recharge a CR123A Battery?IntroductionCR123A Batteries, also known as 123 batteries, are high-capacity lithium-ion batteries that are widely used in security alarm systems. They are the preferred choice of PIR sensor manufacturers in wireless alarm systems due to their high capacity and long life. A CR123A battery can last up to three years in this application before needing to be replaced.This article will teach you everything you need to know about the CR123A battery.Top 5 batteries that will blow your mind!By this video, you will know which CR123A Battery is best for you. Ⅰ CR123A Battery Basics1.1 What is a CR123A Battery?The CR123A battery is a cylindrical cell lithium battery. The shape is reminiscent of a smaller version of a C Cell Battery, or, to put it another way, it resembles a can. These batteries are widely used in a variety of applications, ranging from medical devices to military-grade technology. Because this battery has so many applications, it is very popular and, as a result, can be difficult to find in stock. Furthermore, the lithium nature of the CR123A battery allows for a shelf-life of up to ten years before use, making storage simple. The CR123 battery, also known as CR17345 and DL123A, is used in professional photography equipment. It measures 34mm in height and 17mm in diameter, has a nominal capacity of 1500mAh and can be used to replace the SF123 and Innotek BAT-003 batteries. CR123A battery1.2 Maximum Capacity of the CR123A BatteryCR123A cells have a higher battery capacity, which is typically rated at 1500 mAh. In general, a higher capacity RCR123A cell will have a lower maximum drain rating than a lower capacity RCR123A cell.1.3 The Manner of Applications of the BatteriesThe most noticeable difference between the two types of CR123 batteries is how they both work. A CR123A power cell is a type of battery that is only intended to be discharged, and it must be properly disposed of once it is drained and empty.RCR123A cells, on the other hand, are rechargeable batteries that can be discharged and recharged multiple times. As a result, they are an excellent choice for small electronic devices that are frequently used. Because of this distinction, each type is suitable for a variety of applications.Ⅱ CR123A Battery Specifications2.1 Technical Specifications of the CR123A BatteryCR123A Battery Nominal Voltage:3.2-3.3 VoltsCR123A Capacity (Lithium)≈  1550 mAhCR123A Operating Temperature:-20°C – 75°CCR123A Height:34.2 mmCR123A Width (Diameter):17.0  mmCR123A Chemistry:Lithium Manganese Dioxide2.2 Non-Rechargeable CR123A Battery SpecificationsA non-rechargeable CR123A cell typically has a capacity of 1500 mAh and a nominal voltage of 3 volts. It has a life expectancy of seven to ten years, making it an excellent choice for home security devices and standby electronics that can be used in emergencies.A non-rechargeable CR123A cell is also designed to withstand high current drains, making it an excellent choice for devices that require a large amount of power in a short period.2.3 Rechargeable CR123A (RCR123A) Battery SpecificationsAn RCR123A or rechargeable CR123A battery typically has a capacity of 500 to 800 mAh and a voltage of 3.6 or 3.7 volts. However, as a cell designed to be recharged and used multiple times, RCR123A is a desirable power cell that is recommended for frequently used devices.Ⅲ Top 4 Considerations to Choose the Cr123A Lithium BatteryCR123A batteries are fully charged and ready to use when they arrive in the package. They will typically keep a full or near-full charge for at least ten years. They will also keep a fully charged state for roughly the same amount of time even when stored inside the flashlight.Because CR123A batteries have more capacity than rechargeable batteries, they will have longer run times. Because the voltage remains more constant as the capacity of the battery is depleted by use, the light will typically continue to operate at a reduced output even as the capacity of the battery becomes quite drained.When rechargeable 16340/18650 batteries are stored for up to a year, they gradually lose some of their charges, often up to 30%. Their capacity degrades quickly during use, but they keep the voltage at or above their nominally rated level very well. Rather than gradually dimming, your light will continue to provide full output until the batteries are depleted, at which point it will abruptly stop.A standard CR123A battery may be better for you if your tactical light needs a battery that is ready for immediate use, with full capacity even if it may sit relatively unused for periods.Ⅳ Choosing the Best CR123A BatteriesCR123A batteries are widely used in modern digital cameras, security systems, and even high-output flashlights. Even though there are a plethora of CR123A battery options available, the quality and battery life are far from standard.Best CR123A Battery | Batteries (Top 7 best in 2021)Ⅴ Shopping for CR123A BatteriesBattery life and shelf life are both important considerations when shopping for CR123A batteries because they determine how long your batteries will last while being used in electronic devices or sitting in storage. Another important consideration is compatibility, as not all rechargeable CR123A batteries will work in devices that accept standard CR123As. It is best to check your device's owner's manual before purchasing to ensure that a rechargeable option will work for your device. Finally, consider your electronic device's power consumption. If it consumes a lot of power, consider using high-quality batteries with longer battery life or a rechargeable option to save money in the long run.Ⅵ Why Use the CR123A Battery for Arlo Cameras6.1 Higher VoltageThe CR123A battery has a higher voltage than other batteries, so they can provide enough energy to your Alco Security Camera. The voltage of CR123A batteries is 3.0 volts (nominal). The most common voltage for a CRA123A battery is 3.7 volts.6.2 No Voltage DropsThe constant voltage curve of a Lithium CR123A battery allows for high power. Voltage drops can cause erratic performance, putting a security system's performance in jeopardy, especially if it's connected to a wireless network.6.3 Lighter WeightThe CR123A is lighter than most batteries. Most CR123A batteries are significantly lighter than AA batteries.6.4 Longer Battery LifeThe CRA123A has a battery life of 3 – 5 years on average, which is why it is known as a camera battery. When compared to other types of batteries, these batteries are more durable and last longer.Ⅶ FAQ1. Why is it Called a CR123A?The name of a CR123A cell, like that of many other batteries, contains a wealth of information about its chemistry and size. The CR denotes the battery's chemistry, a prefix used by the IEC to indicate the use of lithium chemistry, specifically LiMnO2. The 23A refers to the battery size, which in this case means that the CR123A is two-thirds the length of a standard A-size battery.2. Are there Rechargeable CR123A Batteries?Yes, but they're also known as RCR123A or 16340 batteries. They are 16mm shorter than CR123As, use lithium-ion chemistries, and typically have lower energy capacities. The RCR123A battery typically has a voltage of 3.6–3.7 volts, and not all flashlights and cameras can use both CR123As and their rechargeable counterparts.3. Can I Use 2 x CR123A Batteries Instead of an 18650 Battery?Occasionally, but not always. Some 18650 battery-powered flashlights and devices have long, spring-loaded interiors to account for varying battery lengths, allowing for the use of two CR123A batteries. Because 18650s are slightly thicker than CR123As, a battery sleeve may be required for a secure connection. We always indicate whether our flashlights are compatible with multiple battery sizes so you don't buy the wrong size cell, and you can shop for CR123A flashlights here.4. Why do I See Names Like EL123A, 123A, and K123LA?These are just variations on CR123As, which can also be referred to as 123, 123A, CR23, and other abbreviations. Some battery manufacturers brand their products, such as Duracell's DL123A and Energizer's EL123A.5. Are all CR123A Batteries the Same?No. The size, terminals, and nominal voltage of the CR123A battery are the same as for any other size. Any CR123A battery should fit in any device that requires one, but this is not always the case, as I discovered when I tried to use some cheap ones in my light meter. However, just like an AA battery, there are cheap ones that may only last an hour or two in a device, whereas a good name brand one may last 5 times as long. Most of the time, you get what you pay for. That Duracell battery will outlast an Amazon Basics or Dollar Store brand battery. And, because a CR123A is a 3-volt battery, some are a single lithium cell, while others are two alkaline cells connected in series. Both are functional, but lithium is more powerful.6. How Long does a CR123A Battery Last?The lifespan of a CR123A battery is heavily dependent on the battery's manufacturing quality and application. Assuming the battery is new and purchased from a reputable source, there is still a wide range of service life available depending on usage. A CR123A battery may last less than a month for a frequent application that requires a large amount of energy, such as a soldier's weapon light. With the right conditions, the service life of a more passive application, such as a home security alarm panel, can be over a year. Essentially, how long your CR123A battery will last is determined by what you require it to do.7. What Battery is Equivalent to the CR123A Battery?Although there are no direct replacements for the CR123A battery, there are batteries that are similar in size but have different chemistries and capabilities. The 16340 battery, for example, is the same size and shape as the CR123A, but it is made of lithium-ion rather than lithium manganese dioxide. This means the 16340 is rechargeable and can be used in the same places as a CR123A. Even though the 16430 battery will fit, it may not perform as well as a CR123A battery or have the same life span.8. Are CR2 Batteries the Same As CR123A?The CR2 battery is not interchangeable with the CR123A battery. Because the CR2 battery is slightly shorter than the CR123A battery, it will not fit in the majority of applications that require a CR123A battery. These batteries do have some similarities, such as the fact that they are both made of lithium manganese dioxide and are both 3 volt batteries. 9. Where to buy CR123A Batteries?CR123A batteries are very common and well-liked. This means that a wide range of manufacturers produces these batteries, and a wide range of retailers sell them. It's important to remember that not all CR123A batteries are created equal, and not all retailers are equally committed to quality. To avoid low-quality or, worse, counterfeit batteries, only purchase your batteries from a highly reputable retailer who sells only the highest-quality brands.10. Are CR123A and CR123 Batteries the Same?Yes. The CR123A and CR123 batteries are interchangeable. These batteries are also known as 123, 123A, DL123, DL123A, and SF123.The letter C in CR123A and CR123 denotes a lithium battery. The letter R stands for round, and the number 123 represents one-third. So 123 batteries are one-third the size of cell batteries. Some manufacturers add the letter A to indicate that the cell is an A cell.11. Can you Recharge a CR123A Battery?The CR123A is a non-rechargeable 3v lithium cell with a 17mm diameter and 34.5mm length. Because it is not rechargeable by definition, the answer is no.However, rechargeable batteries of the same size and voltage as a CR123A are available. A 16340 Li-ion cell, for example, is 16mm diameter and 34.0mm long, with a fully charged voltage of 3.7v, so this would be a compatible battery for some devices - you'd need to check with the device manufacturer.     

Introduction Everyone is familiar with Cameras. Owning a mobile phone is equivalent to owning a smart camera device that is very portable. So what does the camera use to image? And how do you get a clear picture of the object? Here we take you to understand the secrets hidden in the camera. Figure 1. Camera Image Processing Catalog Introduction Ⅰ Photomultiplier Tube (PMT) Ⅱ Charge-coupled Device (CCD) 2.1 CCD Terminology 2.2 CCD Chips 2.3 CCD Types Ⅲ Complementary Metal Oxide Semiconductor (CMOS) 3.1 CMOS Invention 3.2 CCD vs CMOS Ⅳ Imaging System 4.1 Key Elements 4.2 Calculation of Image/Video Data Volume 4.3 Storage Space Calculation 4.4 Camera Composition and Principle 4.5 Intelligent Camera Image Processing Hardware Ⅴ Smart Camera Interfaces and Communication Protocols Ⅵ Image Signal Processor (ISP) Ⅶ FAQ Ⅰ Photomultiplier Tube (PMT) PMT is the earliest image sensor, which is very mature, and it is the sensor with the best performance at present. A photomultiplier tube, useful for light detection of very weak signals, is a photoemissive device in which the absorption of a photon results in the emission of an electron. Because it has multiple electrodes built-in to convert incoming light signals into electrical signals, and even very weak light can be accurately captured. Its highest dynamic range can reach 4.2, compared with other types of sensors that can only reach 3.2~3.6. And it can operate for more than 100,000 hours. However, due to its high cost, it can only be used in professional printing, publishing industry scanners and engineering analysis. Figure 2. Photomultiplier Tube (PMT) Ⅱ Charge-coupled Device (CCD) 2.1 CCD Terminology CCD was invented by Bell Labs in the United States in 1969. It is similar to computer chip CMOS  and can also be used for computer memory and logic operation chips. CCD is a special semiconductor material composed of a large number of independent photodiodes, which are generally arranged in a matrix form (except Fuji's Super CCD). The photosensitive ability of CCD is lower than that of PMT, but in recent years, CCD technology has made great progress, and because of its small size and low cost, it is widely used in scanners, digital cameras and digital video cameras. The image sensors used in most digital cameras today are CCDs.Early CCDs were interlaced (Interline Transfer), which increased the shutter speed, but the image accuracy was greatly reduced. New CCDs are generally progressive scan (FullFrame Transfer). Figure 3. Charge-coupled Device Semiconductor 2.2 CCD Chips It integrates a light-sensitive device on a single piece of semiconductor: a photodiode and some circuits. Each unit is arranged in a neat matrix, CCD pixel = number of rows multiplied by the number of columns. About 30% of each pixel cell is used to make photodiodes, and in the remaining available area, a transfer register is placed. After receiving a command, the light intensity sensed by the photodiode is placed in this transfer register and temporarily stored here, which is an analog signal. The next step is to convert the light intensity value in each pixel into a digital signal, which is then combined into a digital image by the processor in the camera.Since in each pixel unit, only about 30% of the area is actually used for light-sensing, its light-sensing efficiency is relatively low. So in the real finished product, a small optical lens will be placed on top of each pixel unit, which we call "microlens". In terms of structure, it is directly placed above the photodiode, and its area is relatively large, so that more incident light can be concentrated on the photodiode. Therefore, the equivalent photosensitive area reaches about 70% of the pixel area. 2.3 CCD Types Primary color CCD and complementary color CCD: In fact, the CCD itself cannot distinguish colors. Therefore, color filters are required in practical applications. Generally, the filter layer of the CCD device is coated with different colors. The different color blocks on the filter are arranged like a mosaic in the order of G-R-G-B (green-red-green-blue), so that the pixels under each mosaic can sense different colors. Figure 4. Color Filter Array Sensor For example, a 1.3-megapixel CCD has 325,000 pixels sense red, 325,000 pixels sense blue, and 650,000 pixels sense green. In a digital camera with a resolution of 1280x1024 using this CCD, there are 640x512 red pixels, 640x512 blue pixels and 640x1024 green pixels, having more green pixels due to the human eye's sensitivity to green and other color is not the same. Finally, when the image is recorded, the true color of each pixel is the average of its blending with the surrounding pixel image. At present, most digital cameras use this kind of CCD.Linear CCD, different from matrix CCD, may be arranged in a linear arrangement of photosensitive elements, so it is a strip, like barcode scanners.   Ⅲ Complementary Metal Oxide Semiconductor (CMOS) 3.1 CMOS Invention CMOS was not used to make image sensors until 1998. The advantage of CMOS is that the structure is simpler than that of CCD, the power consumption is only about 1/3 of that of ordinary CCD, and the manufacturing cost is lower than that of CCD. Since Canon adopted CMOS in the professional digital SLR camera EOS D30, more and more digital SLR cameras have used it, and almost half of the digital SLR cameras now use CMOS as the image sensor. Figure 5. Complementary Metal Oxide Semiconductor (CMOS) 3.2 CCD vs CMOS CCD and CMOS sensors are different in "internal structure" and "external structure". The imaging points of the CCD device are arranged in an XY vertical and horizontal matrix, and each imaging point consists of a photodiode and a charge storage area controlled by it. Where the CCD can only output analog electrical signals, which need to be decoded by subsequent addresses. Further more, it also needs to provide three-phase power supply and synchronous clock control circuit with different voltages.CMOS devices have high integration, small size and light weight. Its biggest advantage is that it has a high degree of system integration. Because of the digital-analog signal mixed design, in theory, all functions required by image sensors, such as vertical displacement, horizontal displacement register, sensor array drive and control system (CDS), analog-to-digital converter (ADC) interface circuit, etc. can be fully integrated to achieve single-chip imaging, avoid the use of external chips and equipment, and greatly reduce the size and weight of the device.The charge information stored by the CCD needs to be read after being transferred bit by bit under the control of the synchronization signal. The charge information transfer and read output need to be coordinated by a clock control circuit and three sets of different power supplies. slower. The CMOS photoelectric sensor directly generates a voltage signal after photoelectric conversion, the signal reading is very simple, and it can also process the image information of each unit at the same time, which is much faster than CCD.From the perspective of power consumption and compatibility, CCD requires external control signals and clock signals to obtain satisfactory charge transfer efficiency, and also requires multiple power supplies and voltage regulators, so the power consumption is large. While CMOS-APS uses a single operating voltage, with low power consumption (only equivalent to 1/10-1/100 of CCD) and good compatibility, can also be compatible with other circuits.CCD sensors require special processes, use special production processes, and have high costs; while CMOS sensors use 90% of the same basic technologies and processes as semiconductor devices, and have high yield and low manufacturing costs. Currently, 500,000-pixel CMOS sensors are used for cameras.CCDs use charge shift registers, and when the register overflows, it leaks charge into adjacent pixels, causing the bright light to spread out and create unwanted streaks in the image. In CMOS-APS, the photodetector and the output amplifier are both part of each pixel. The integrated charge is converted into a voltage signal in the pixel and output through the XY output line. This row-column addressing method makes the window operation possible. You can also perform on-film translation, rotation and zooming, without smear, halo and other false signals, to get high image quality.High speed is an inherent characteristic of CMOS circuits. CMOS image sensors can drive the column bus of the imaging array extremely fast, and the ADC operates at an extremely fast rate on-chip, and has low sensitivity to output signals and external interface interference, which is beneficial to next level processor connection. CMOS image sensors are highly flexible and can perform random access to local pixel images, increasing flexibility. Camera Image Sensors as Fast As Possible   Ⅳ Imaging System 4.1 Key Elements 1) Field of View: The portion of an object that can be seen on a display.2) Depth of Field: The difference between the nearest and farthest distances at which an imaging system can remain in focus.3) Working Distance: When observing an object, the distance from the vertex of the last lens to the observed object.4) Distortion: The optical error caused by the lens makes the magnification of each point on the image surface different.5) Parallax: It is caused by the traditional lens, the change of each point on the object outside the best focus point, the telecentric lens can solve this problem.6) Image Sensor Size: The effective working area of the image sensor (usually CCD or CMOS), generally refers to the horizontal size. This parameter is important in determining the pre-magnification factor (PMAG) for the desired field of view. Most image sensors have a length to width ratio of 4:3.7) Pre-magnification: It refers to the ratio of the field of view to the size of the image sensor, which is done by the lens.8) System Magnification: It refers to the ratio of the image on the display to the actual size of the object, that is, the magnification of the entire system. It can also be written as the product of pre-magnification and electronic magnification, which is the ratio of display size to image sensor size.9) Resolution: The distance between two points on an object that can be minimally distinguished, indicating the ability to distinguish details. 4.2 Calculation of Image/Video Data Volume Definition of picture resolution in different camera pixels (number of photosensitive elements of CCD/CMOS sensor):FCIF (Full Common Intermediate Format) Resolution: 352*288=100,000 pixels DCIF Resolution: 512*384=200,000 pixelsD1(4CIF) Resolution: 704*576=400,000 pixels720P Resolution: 1280*720=1 million pixels1080P Resolution: 1920*1080=2 million pixels Figure 6. Camera Pixel Art The computer's true color pixels are stored according to the RGB three-color principle, and each color of red, green and blue is 256 (2 to the 8th power, one byte length), so a pixel needs 3 bytes and 24 bits. Now that the calculation capacity is large, a 256 grayscale is added on the basis of RGB storage, so 4 bytes are needed, that is, 32 bits. In addition, such pixels are now also called true color.Bit rate refers to the number of bits transmitted per second. The unit is bps (bit Per second). The higher the bit rate, the larger the data transmitted. The bit rate indicates how many bits per second the encoded (compressed) audio and video data needs to be represented, and a bit is the smallest unit in binary, either 0 or The relationship between bit rate and audio and video compression is simply that the higher the bit rate, the better the quality of audio and video, but the larger the encoded file. If the bit rate is lower, the situation is just the opposite.DataRate refers to the data flow used by video files in unit time, also called bit rate, which is the most important part of picture quality control in video coding. Under the same resolution, the larger the code stream of the video file, the smaller the compression ratio and the higher the image quality.1) 720P single image data volume = 1280 × 720 × 24/8/1024 = 2700 KByte.2) The amount of data of the moving image3) H.264 compressed payload data volumeThe biggest advantage of H.264 is that it has a high data compression ratio. Under the same image quality, the compression ratio of H.264 is more than 2 times that of MPEG-2, and 1.5 to 2 times that of MPEG-4. For example, the original file is 88GB, 3.5GB after MPEG-2 compression, the compression ratio is 25:1, and the H.264 compression is 1.1GB, from 88GB to 1.1GB, the compression ratio of H.264 reaches 80:1. For example, in the video conference, the original code stream is encoded and compressed by adopting H.264.4) The amount of transmitted data compressed by H.264Adding network overhead, the amount of data transmitted = the amount of payload data * 1.3At 20%, the amount of data transmitted after compression = 1.6 * 1.3 = 2.08 Mbit/s5) Home monitoring storage capacityBandwidth Calculation:The required bandwidth of the CIF video format: 512Kbps (the bit rate of the video format) × 50 (the total number of cameras at the monitoring point)=25Mbps (downlink bandwidth). That is: the network downlink bandwidth required by the monitoring center using CIF video format is at least 25Mbps.The required bandwidth of the D1 video format: 1.5Mbps (bit rate of the video format) × 50 (the total number of cameras in the monitoring point) = 75Mbps (downlink bandwidth). That is: the network downlink required by the monitoring center using D1 video format bandwidth is at least 75Mbps.The required bandwidth of 720P (1 million pixels) video format: 2Mbps (bit rate of video format) × 50 (the sum of the total number of cameras at the monitoring point) = 100Mbps (downlink bandwidth). That is: adopting 720P video format monitoring, the network downlink bandwidth required by the center is at least 100Mbps.The required bandwidth of the 1080P (2 million pixel) video format: 4Mbps (bit rate of the video format) × 50 (the total number of cameras at the monitoring point) = 200Mbps (downlink bandwidth) That is: adopting 1080P video format monitoring, the network downlink bandwidth required by the center is at least 200Mbps. 4.3 Storage Space Calculation Stream size (unit: KB/s; namely: bit rate ÷ 8) × 3600 (unit: second; seconds in 1 hour) × 24 (unit: hour; length of one day) × 30 (days saved) × 50 (the total number of camera recordings to be saved at the monitoring point) ÷ 0.9 (10% space loss from disk formatting) = the size of the required storage space (Note: unit conversion 1TB=1024GB, 1GB=1024MB, 1MB=1024KB)The required storage space for 50 channels to store 30 days of CIF video format video information is: 64 × 3600 × 24 × 30 × 50 ÷ 0.9=8789.1GB ≈ 9TBThe required storage space for 50 channels to store 30 days of D1 video format video information is: 192 × 3600 × 24 × 30 × 50 ÷ 0.9=26367.2GB ≈ 26TBThe required storage space for 50 channels of 720P (1 million pixels) video format recording information for 30 days is: 256 × 3600 × 24 × 30 × 50 ÷ 0.9=34.33GB ≈ 35TBThe required storage space for 50 channels of 1080P (2 million pixels) video format video recording information that can be stored for 30 days is: 512 × 3600 × 24 × 30 × 50 ÷ 0.9=68.66GB ≈ 69TB 4.4 Camera Composition and Principle The working principle of the camera is to project the optical signal obtained by the optical component onto the image sensor, complete the conversion from the optical signal to the electrical signal, and then convert it into a digital image signal, and finally perform the algorithm processing of the signal. The main components of the camera are optical components lens, CMOS sensor, DSP, module assembly and other components. 4.5 Intelligent Camera Image Processing Hardware Image processing capability: FPGA<DSP<High-end CPUASICs are ideal for performance and power consumption. Develop a dedicated SoC (system on chip) for a given application, implement a custom architecture to accommodate data flow, and optimize power consumption. However, the development cost is high and it is suitable for consumer products (i.e. production volumes of thousands of units). ASIC devices have very little or zero flexibility and programmability due to their specificity.FPGAs are the best choice for low- or medium-volume high-performance applications. They are very flexible and can meet the requirements of almost any application. Due to the ever-increasing number of available logic elements per device in FPGAs, increasing clock frequencies, and the possibility to exploit massive parallelism, it is possible to achieve processing performance close to ASICs, with the advantage of being fully reconfigurable. However, the power consumption of FPGAs is relatively high, and even if design methodologies and development environments exist, FPGA-based solutions require more development time and expertise than CPU-based solutions (DSP, microcontroller, etc.).DSP devices and media processors share many characteristics with embedded general-purpose RISC processors (PowerPC, ARM, etc.) and microcontrollers. All these devices are CPU based, i.e. based on processor cores. Therefore, they all have excellent programmability, using programming tools such as C/C++ and dedicated development environments. NRE (non-recurring engineering) is very low cost and has good flexibility, so it is suitable for most applications.The main difference between CPU-based devices comes at the performance level. A microcontroller can be seen as an enhanced RISC processor by adding CPU core memory (RAM, ROM, Flash), peripherals and I/O interfaces (ADC, DAC, etc.). In addition, the DSP core provides a dedicated architecture and some specific hardware structures to optimize the execution of arithmetic operations, such as MAC (multiply-accumulate) and SIMD units. Finally, media processors are a class of DSP devices dedicated to audio and video processing, suitable for processing data streams. DSPs and media processors may have a VLIW (Very Long Instruction Word) architecture, such as NXP TriMedia processors. Figure 7. Camera Color Coding Ⅴ Smart Camera Interfaces and Communication Protocols Wired Interface and Wireless Interface Table 1. Most Common Wired Communication Protocols Protocol Theoretical Bandwidth in bits per second (bit/s) RS-232 serial link USB 1.x Full-speed USB 2.0 Hi-speed FireWire or IEEE 1394a/b Camera Link Ethernet, Fast Ethernet GigE Vision (Gigabit Ethernet) 19,200 bit/s 12 Mbit/s 480 Mbit/s 400/800 Mbit/s 2.04, 4.08, or 5.44 Gbits 10/100 Mbit/s 1 Gbit/s   Table 2. Most Common Wireless Protocols Protocol Theoretical Bandwidth (bit/s) Wireless Range (m) WiFi IEEE 802.11a WiFi IEEE 802.11b WiFi IEEE 802.11g Bluetooth ZigBee (IEEE 802.15.4) 54 Mbit/s 11 Mbit/s 54 Mbit/s 1 Mbit/s 250 Kbit/s Up to 10m ~50m indoor, ~200m outdoor ~27m indoor, ~75m outdoor ~10-100m ~10-100m indoor, up to 150m outdoor For example, if the camera is equipped with the MT9M413 image sensor from Aptina Imaging (formerly Micron Imaging), capable of delivering images up to 660M pixels/s, a camera interface is required to take full advantage of the sensor (5.44 Gbit/s (680 M Bytes/s in full configuration) ). However, if there are other constraints, the rules of keeping data rates compatible between sensors and communication interfaces may be broken. For example, with a battery-operated smart camera, even real-time video transmission with a bandwidth of 250 Kbit/s makes no sense. There are two workarounds:1) Wireless ZigBee protocol, because its power consumption is very low.2) Another solution to reduce bandwidth requirements is an image compression algorithm. However, compressing and decompressing images places additional processing burden on the camera and host, and can result in loss of picture quality, depending on the desired compression ratio.And bandwidth isn't the only deciding factor. For example, GigE Vision systems are inexpensive to implement, but the end result can hinder application responsiveness and development time. GigE Vision is still in its infancy, while Camera Link and IEEE 1394 have proven. The integrity of the standard must also be considered. GigE Vision and IEEE 1394 cameras are compatible between vendors and are easier to configure than Camera Link.   Ⅵ Image Signal Processor (ISP) It is widely used in mobile phone cameras and car cameras and other fields, and is the core chip of image signal processor.ISP pipeline process: The light passes through the lens, after lens correction and color correction, is projected onto the sensor, photoelectrically converted into an analog electrical signal, and then converted into a digital signal by A/D, and then handed over to the ISP chip for processing. Then, the obtained image of the bayer pattern goes through BLC (black level compensation), lens shading (lens shading correction), BPC (bad pixel correction), CIP (demosaic), DNS (denoise), AWB (automatic white balance), color correction gamma correction, color space conversion (RGB conversion YUV), and then output data in YUV (or RGB) format, and finally transmitted to the CPU for processing through the I/O interface.The functions of each module are briefly described as follows:1) Bayer PatternThe filters that cover the surface of the image sensor are usually called Color Filter Arrays (CFA). At present, the most commonly used filter array is in checkerboard format, and the primary color Bayer Pattern CFA RGB represents the filter array unit of red, green and blue. Since human vision is most sensitive to green, the G component in Bayer CFA is twice that of R and B, and only one color component information can be obtained on each pixel, and then an interpolation algorithm is passed according to the color component information, finally get a full color image.2) Black Level Correction (BLC)Physical devices cannot be ideal. Due to impurities, heat and other reasons, even if no light is irradiated to the pixel, the pixel unit will generate charges, and these charges generate dark current. Moreover, dark current is difficult to distinguish from the charge generated by light. Black Level is used to define the signal level corresponding to 0 for image data. An effective way to reduce the influence of dark current on the image signal is to subtract the reference dark current signal from the obtained image signal. Generally, in the sensor, the first few lines of the pixel area are used as the non-photosensitive area. This part of the area is also used for RGB color filter. The average value is used as the correction value for automatic black level correction, and then the pixels in the following area are subtracted from this. Pay attention to, the brightness of the picture is reduced after black level correction.3) Lens Shading Correction (LSC)Due to the physical properties of the lens itself, the brightness around the image gradually decreases relative to the center brightness. When the image light shines on the pixel through the lens, the focus angle at the corners is greater than the center focus angle, resulting in loss of light at the corners. In order to compensate for the surrounding brightness, Lens Shading correction is necessary. The method is to calculate the brightness correction value corresponding to each pixel according to the algorithm, so as to compensate the brightness of the surrounding attenuation.4) Bad Pixel Correction (BPC)Under normal circumstances, the RGB signal should have a linear response relationship with the brightness of the scene. However, due to the bad pixels of senor, the output signal is abnormal, and there are dead spots: white spots in the output image in a dark environment, and black spots in the output image in a bright environment. There are usually two methods of repairing dead pixels: one is to automatically detect and repair the dead pixels, and the other is to establish a linked list of dead pixels to repair bad pixels at fixed positions. This method is the OTP method. 5) DNSUsing CMOS sensor to acquire images, light level and sensor issues are the main factors that generate a lot of noise in the image. At the same time, when the signal passes through the ADC, some other noise is introduced. These noises will blur the image as a whole and lose a lot of details, so the image needs to be denoised. The traditional methods of spatial denoising include mean filtering, Gaussian filtering and so on. However, the general Gaussian filter mainly considers the spatial distance relationship between pixels when sampling, and does not consider the similarity between pixel values, so the blurring result obtained in this way is usually a blur of the entire picture. Therefore, a nonlinear denoising algorithm, such as bilateral filter, is generally used, which not only considers the relationship between pixels in spatial distance, but also considers the similarity between pixels, so that the general segmentation of the original image can be maintained to keep the edge. In practical applications, wavelet denoising is more suitable, and each segment in the entire pipeline will be more or less applied to DNS, which is particularly important in the entire process of ISP, and exists in almost every part of it.6) Color InterpolationWhen the light passes through the Bayer-type CFA array, the light hits the sensor, and the BGR data is obtained respectively. Here, the data sampling ratio of BGR is 1:2:1, because the human eye is more sensitive to green light (550nm). Among them, G is also called luminance information, and BR is chrominance information. It can be seen that in the above Bayer diagram, each pixel has only one of the BGR data, so it is necessary to use CIP interpolation to supplement the color information of the other two channels to form a normal full-color image.7) Automatic White Balance (AWB) The basic principle of automatic white balance is to restore white objects to white objects in any environment, that is, by finding white blocks in the image, and then adjusting the ratio of R/G/B.The AWB algorithm usually steps as follows:Color temperature statistics, according to the image statistics color temperature.Calculate channel gain: Calculate the gain of R and B channels.Correction of color cast: Calculate the correction of color cast according to the given gain. Grayscale world method and perfect reflection method are more commonly used and effective.8) Gamma CorrectionThe sensitivity value of the human eye to the external light source is not linearly related to the input light intensity, but is exponentially related. Under low illumination, it is easier for the human eye to distinguish the change of brightness. With the increase of illumination, it is difficult for the human eye to distinguish the change of brightness. However, there is a linear relationship between the light sensitivity of the camera and the input light intensity. In order to help the human eye to recognize the image, the image collected by the camera needs to have Gamma correction. It is a nonlinear operation on the gray value of the input image, so that the gray value of the output image has an exponential relationship with the gray value of the input image.9) Color CorrectionDue to the difference between the spectral responsivity of the visible light of the human eye and the spectral responsivity of the semiconductor sensor, as well as the influence of lenses, etc., the color of the obtained RGB value will be biased, so the color must be corrected. The usual method is to pass a 3x3 Color change matrix for color correction.10) RGB Conversion YUV Color Space ConversionYUV is a basic color space, and the human eye is much more sensitive to changes in brightness than changes in color. Therefore, for the human eye, the brightness component Y is much more important than the chrominance components U and V. Therefore, some U and V components can be appropriately discarded to achieve the purpose of compressing data.Laplacian operator: YCbCr is actually a scaled and offset modified version of YUV, Y represents the brightness, Cr and Cb represent the color difference, which are the red and blue components respectively. In the YUV family, YCbCr is the most widely used member in computer systems, and its application fields are very wide. For example, JPEG and MPEG both use this format. Generally speaking, YUV mostly refers to YCbCr.The color space conversion module converts RGB to YUV444, and then performs subsequent color noise removal, edge enhancement, etc. on the YUV color space, which also provides convenience for subsequent output conversion to JPEG images.   Ⅶ FAQ 1. Does photomultiplier tube PMT scan images?Photomultiplier tubes (PMTs), also known as photomultipliers, are remarkable devices. While a PMT was the first device to detect light at the single-photon level, invented more than 80 years ago, they are widely used to this day, particularly in biological and medical applications. 2. Why are photomultiplier tubes so sensitive?Photomultipliers (sometimes called photon multipliers) are a type of photoemissive detectors which have a very high sensitivity due to an avalanche multiplication process, and also exhibit a high detection bandwidth. 3. What does CCD stand for in cameras?CCD stands for "charge coupled device", a semiconductor image sensor used in digital cameras to convert light into electrical signals. In place of the film used in conventional film cameras, digital cameras incorporate an electronic component known as an image sensor. 4. What are CCD sensors used for?CCDs are used in optical microscopes because they can possess over 10 million pixels, which enables many samples to be seen clearly, as well as a low noise ratio, ability to image in color, high sensitivity and a high spatial resolution which all contribute to the high-quality images that are necessary for modern-day. 5. What is good camera pixels?A decent 6-megapixel camera is good enough for most normal camera usage. Go for higher megapixels only if you wish to use your images for canvas-sized prints or large hoardings. If your interest is in night sky photography, then too a higher megapixel camera can be important. 6. What is resolution in camera settings?A picture's resolution describes how many pixels, or dots, are in the image. The more dots, the better the image looks and prints. Megapixel is a measurement of the amount of information stored in an image. 7. What is a good camera resolution?A Camera Resolution Reference Chart Resolution Avg. Quality Best Quality 0.5 megapixels 2x3 in. NA 3 megapixels 5x7 in. 4x6 in. 5 megapixels 6x8 in. 5x7 in. 8 megapixels 8x10 in. 6x8 in. 8. What is H264 format?H. 264 is a well-known video compression standard for high-definition digital video. Also known as MPEG-4 Part 10 or Advanced Video Coding (MPEG-4 AVC), H. 264 is defined as a block-oriented, compensation-based video compression standard that defines multiple profiles (tools) and levels (max bitrates and resolutions). 9. Which is better H 264 or H 265?265 codec compresses information more efficiently than H. 264, resulting in files of comparable video quality that are about half the size. The benefits of this are twofold: H. 265 video files don't take up as much storage space, and they require less bandwidth to stream. 10. What is a camera chip?Able to leap photographic obstacles with a single computer chip. It's a camera. It's a chip. It's a camera-on-a-chip. ... Most of today's digital cameras use charge-coupled device (CCD) sensors rather than the far less expensive complementary metal-oxide semiconductor (CMOS) chips used in most computing technologies. 11. Is CCD better than CMOS?For many years, the charge-coupled device (CCD) has been the best imaging sensor scientists could choose for their microscopes. ... CMOS sensors are faster than their CCD counterparts, which allows for higher video frame rates. CMOS imagers provide higher dynamic range and require less current and voltage to operate. 12. What is camera image sensor?The image sensor of the camera is responsible for converting the light and color spectrum into electrical signals for the camera to convert into zeroes and ones. All commercially available digital cameras (still, movie, or security) use one of two possible technologies for the camera's image sensor: CCD or CMOS. 13. How do photomultiplier tubes detect light?The reflection mode photocathode is mainly used for the side-on photomultiplier tubes which receive light through the side of the glass bulb, while the transmission mode photocathode is used for the head-on photomultiplier tubes which detect the input light through the end of a cylindrical bulb. 14. Which interface is used for camera?The most common USB 3.1 connector used in the machine vision camera industry is the USB 3.1 Micro B connector. Gradually being introduced to the market is USB-C (USB Type C), the connection type designed for the future. 15. Which of the serial communication standard is used in digital camera?Camera LinkCamera Link is a serial communication protocol standard designed for camera interface applications based on the National Semiconductor interface Channel-link. It was designed for the purpose of standardizing scientific and industrial video products including cameras, cables and frame grabbers. 16. What does image signal processor do?As the name implies, the Image Signal Processor (ISP) is used for processing images in embedded vision camera systems. The ISP also performs other operations on the captured image such as demosaicing, denoising, and auto functions that help deliver an enhanced image. 17. What is image and signal processing?The field of signal and image processing encompasses the theory and practice of algorithms and hardware that convert signals produced by artificial or natural means into a form useful for a specific purpose. ... Image processing work is in restoration, compression, quality evaluation, computer vision, and medical imaging. 18. Where are DSP processors used?DSP is used primarily in areas of the audio signal, speech processing, RADAR, seismology, audio, SONAR, voice recognition, and some financial signals. For example, Digital Signal Processing is used for speech compression for mobile phones, as well as speech transmission for mobile phones. 19. What is RGB conversion?RGB to hex conversionConvert the red, green and blue color values from decimal to hex. Concatenate the 3 hex values of the red, green and blue togather: RRGGBB. 20. What is AWB setting?One of the white balance settings, "Auto White Balance" (AWB) automatically adjusts to correct the changes in color under different light sources. The function adjusting the color tone so that white objects look white in the picture is called white balance (WB).