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 The heat sink has a thermal conductor that carries heat away from the device into fins that provide a large surface area for the heat to dissipate throughout the rest of the components, thus cooling both the heat sink and processor. Both a heat sink and a radiator require airflow and, therefore, both have fans built-in. At present, the main failure form of electronic equipment is thermal failure. According to statistics, 55% of failure of electronic equipment is caused by temperature exceeding the rated value. With the increase of temperature, the failure rate of electronic equipment increases exponentially. Therefore, the thermal design of power devices is most important in the structural design of electronic equipment, which directly determines the success of the products. Good thermal design is the basis for the stable and reliable operation of the equipment. Electronics Thermal Heatsink Design Tutorial CatalogI. Main Parameters of Thermal PropertiesII. Thermal Design of Power DeviceIII. Heat Dissipation CalculationIV. Calculation ExampleV. Selection of RadiatorVI. ConclusionFAQ I. Main Parameters of Thermal Properties The thermal stress of the power device can come from the inside of the device or from the outside of the device. If the heat dissipation capacity of the device is limited, the consumption of power will lead to the rise of temperature and junction temperature in the active region of the chip inside the device, reducing the reliability of the device lower and making the device unable to work safely. The main parameters to characterize the thermal capacity of power devices are junction temperature and thermal resistance. The active region of the device can be the PN junction region of the junction device (such as a transistor), the channel region of the field-effect device, the diffused resistor, or the thin film resistance of the integrated circuit, and so on.  When the junction temperature Tj is higher than the ambient temperature Ta, the heat through the temperature difference to form a diffusive heat flow, which is emitted from the chip through the tube shell, and the heat emitted increases with the increase of the temperature difference (Tj-Ta).  In order to ensure that the device can work properly for a long time, an allowable maximum junction temperature Tj max has been made. Tj max is determined by chip materials, packaging materials, and reliability of devices. The heat dissipation ability of power devices is usually characterized by thermal resistance, called Rt. The larger the thermal resistance is, the worse the heat dissipation ability is. Thermal resistance is also divided into internal thermal resistance and external thermal resistance.  Internal thermal resistance is the inherent thermal resistance of the device itself, which is related to the thermal conductivity, thickness, and cross-sectional area of the tube core, shell material, and processing technology, while external thermal resistance is related to the form of tube package. Generally speaking, the larger the shell area, the smaller the external thermal resistance. The external thermal resistance of the metal shell is obviously lower than that of the plastic. When the power consumption reaches a certain level, the junction temperature of the device goes up and the reliability of the system decreases. In order to improve the reliability, the thermal design of the power device should be carried out.  II. Thermal Design of Power Device The thermal design of the power device is mainly to prevent thermal failure caused by overheating or alternating temperature. It can be divided into the thermal design of the internal chip, thermal design of the package, thermal design of the tube, and thermal design in practical use. For general power devices, only the thermal design of the device's interior, package, and the tube should be considered. But when the power consumption is high, the appropriate radiator should be installed, through which the heat can be effectively dissipated to ensure the device works normally and reliably within the safe junction temperature.   III. Heat Dissipation CalculationThe most commonly used heat dissipation method is to install the power device on the radiator, using the radiator to disperse the heat into the surrounding, if necessary, to add the fan to strengthen the heat dissipation with a certain wind speed.  Flow cold water cooling plate is also used in some large power devices, which has a better heat dissipation effect. Heat dissipation calculation is to determine the appropriate heat dissipation measures and radiators through calculation under certain working conditions. There is a certain thermal resistance in the heat transfer process. The thermal resistance from the core of the device to the bottom is Rjc, between the bottom and the radiator is Rcs, a radiator that spreads heat into the surrounding is Rsa, the total resistance is Rja=Rjc+Rcs+Rsa.  If the maximum power loss of the device is Pd, and the permitted junction temperature of the device is Tj, ambient temperature is Ta, the reasonable total thermal resistance Rja can be obtained by the following formula.Rja ≤(Tj-Ta)/Pd The thermal resistance of the maximum allowable Rsa is: Rsa ≤(Tj-Ta)/Pd-(Rjc+Rcs) For design consideration, Tj is generally set to 125℃, Ta=40℃ ~ 60℃ generally used in the case of bad ambient temperature. The size of Rjc depends on the size of the core and the package structure, which can be found from the parameter list. Rcs size depends on the installation technology and device packaging. If the device adopts heat conducting grease or heat transfer pad, installing with the radiator, the typical value of Rcs is 0. 1 ℃/W / ~ 0. 2 ℃/W; If the bottom surface of the device is not insulated and additional mica insulation is required, the Rcs can reach 1 ℃/W. Pd is the maximum power loss calculated according to the working conditions of different devices. In this way, Rsa can be calculated to select an appropriate radiator. IV. Calculation ExampleA power operational amplifier PA02 as low-frequency power amplifier, the device is 8-pin and TO-3 metal shell package. The operating conditions are as follows: the operating voltage Vs is 18 V, the load impedance RL is 4Ω, the ambient temperature is 40 ℃, and the natural cooling is adopted. According to the data of PA02: the typical value of static current Iq is 27mA, the maximum value is 40mA, and the typical value of Rjc (from tube core to shell) is 2.4 ℃/W, and the maximum value is 2.6 ℃/W. The power consumption of the device is Pd=Pdq+ Pdout(Pdq is the internal power consumption and Pdout is the output power consumption). The calculation is as follows: Pdq=Iq(Vs+|-Vs|)  Pdout=Vs2/(4RL)  Iq=37mA                                                                                 Pd=Iq(Vs+|-Vs|)＋Vs2/(4 RL)                                                                                     =0.037×(18+18)＋182/(4×4)                                                                                     =21.6 W Radiator thermal resistance: Rsa ≤(Tj-Ta)/Pd-(Rjc+Rcs) Tj=125℃, Ta=40℃, Rjc=2.6℃/W, Rcs=0.2℃/W(PA02 installed directly on radiator with heat conductive grease in the middle) Substitute the above data into the formula to get Rsa≤ (125-40)/21.6-(2.6+0.2)≤ 1.135℃/W The thermal resistance HSO4 in natural convection is 0. 95 ℃/W, which can meet the requirement of heat dissipation. V. Selection of RadiatorRadiators are generally standard parts, but also provide customization. The surface of the radiator is treated by electrophoretic coating or black oxygen polarization, which aims to improve heat dissipation and insulation performance.  In natural cooling can be increased by 10%~15%, in ventilation cooling can be increased by 3%, and electrophoretic coating can withstand pressure 500V~800V. The heat resistance of different types of radiators in different heat dissipation conditions is given by the radiator manufacturers. The radiator is used to control the temperature of the power device, especially the junction temperature (Tj), making is lower than the safe junction temperature of the power device, so as to improve the reliability of the power device.  Conventional radiators tend to be standardized, serialized, universal, and new products develop towards low thermal resistance, multifunction, small volume, lightweight, and suitable for automatic production and installation.  The internal thermal resistance of various power devices is different and the difference of contact surface and installation torque will lead to the thermal-resistance difference between the contracts.  The main factor of selecting a radiator is the heat resistance Rtf. Under different environmental conditions, the heat dissipation of power devices is also different. Therefore, environmental factors, the matching between radiator and power device, and the volume and quality of the whole electronic equipment should be taken into account in selecting the appropriate radiator. First of all, according to the performance parameters and environmental parameters of the power device in normal operation, calculate whether the junction temperature of the power device is within the safe condition, determine whether it is necessary to install the radiator, and calculate the corresponding thermal resistance of the radiator if it needs to be installed.  The junction temperature of the power device is recalculated to determine whether the junction temperature of the power device is within the range of safe junction temperature, so as to judge whether the selected radiator meets the requirements. For the radiator that meets the requirements, the optimum design should be carried out according to the actual engineering requirements.   VI. ConclusionThrough the analysis and calculation of the heating principle of the power device, it can guide the design of the heat dissipation mode and the selection of the radiator, ensure the power device work in the safe temperature range, reduce the quality problem, and improve the reliability of the electronic products.  The reliability of electronic equipment is also related to the components, structure, assembly, process, processing quality, and so on. In practical engineering applications, feedback data should be obtained through various tests to perfect the design and further improve the reliability of electronic equipment. FAQ 1. What is a heat sink and how does it work?A heat sink (also commonly spelled heatsink) is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant, where it is dissipated away from the device, thereby allowing regulation of the device's temperature. 2. What is a heat sink used for?A heat sink is a component that increases the heat flow away from a hot device. It accomplishes this task by increasing the device's working surface area and the amount of low-temperature fluid that moves across its enlarged surface area. 3. Does a heat sink need a fan?Most heatsinks have denser fins, which requires a fan to be mounted directly on the cooler. If your heatsink has heat pipes (copper tubes running through the fins), then it's most likely designed to be used with a fan. It's simple to test whether or not a heatsink can safely be run without a fan on it. 4. What material dissipates heat the best?Thermal conductivity is the measure of a metal's ability to conduct heat. What this means is that that the metal acts to cool temperatures, through a process of dissipation. The metals with the highest thermal conductivity are copper and aluminium. The lowest are steel and bronze. 5. How many types of heat sinks are there?The Two Major Heat Sink Categories. All heat sinks can be broken down into two major categories… active and passive. 6. What is the difference between active and passive heat sinks?An active heat sink has a fan attached to it, to actively pull heat away from the heat sink and chip that lies underneath it. A passive heat sink is just a heat sink, a piece of flat metal with fins on top that directs heat away from the chip set it is installed on. 7. Which is better heat sink or fan?Generally though, with good airflow provided by the fan heatsinks can often be a lot smaller. The only benefit to a heatsink-only arrangement is less noise. ... Out of preference you want the heatsink fins to be standing upwards so that hot air can immediately rise off of it and cool air be pulled in. 8. What is the difference between a heatsink and a CPU fan?The heatsink draws the heat away from the CPU, and the fan ensures a steady stream of air for the heatsink to pass the heat to. However, there is more to selecting a heatsink and fan than just looking for a good price or one that looks cool. 9. What is the difference between a heat sink and a heat pipe?Vapor chambers are most often used to spread heat to a local heat sink, whereas heat pipes are generally better for moving heat to a remote sink. ... If you need a heat sink that's minimally 10 times, but usually closer to 20 times, the area of the heat source, consider vapor chambers. 10. How is a heat sink attached to an electrical component?A heat sink is a mechanical component that is attached to an electrical component for the sake of transferring heat from the electrical component into the surrounding environment. This environment is most commonly air, but it can also be other fluids, such as water or coolant. 

The solid-state capacitor is called a solid-state aluminum electrolytic capacitor. The biggest difference between it and ordinary capacitors (i.e. liquid aluminum electrolytic capacitors) lies in the use of different dielectric materials. The dielectric materials of liquid aluminum capacitors are electrolyte, while the dielectric materials of solid capacitors are electroconductive polymer materials.   Electronic Basics #14: Capacitors Catalog I. Solid State Capacitor Introduction II. Solid State Capacitor Advantages III. Solid State Capacitor Types IV. Advantages and Disadvantages of Solid Capacitors FAQ   I. Solid State Capacitor Introduction   In view of the many problems of liquid electrolytic capacitance, the solid aluminum electrolytic capacitor has emerged as the times require. Since the 1990s, solid conducting polymer material has been used as cathode instead of electrolyte for aluminum electrolytic capacitor, which has achieved great development. The conductivity of conductive polymer materials is usually 2 ~ 3 orders of magnitude higher than that of electrolytes.    The application of aluminum electrolytic capacitors can greatly reduce the ESR and improve the features of temperature frequency, what’s more, because of the good processability of polymer materials, it is easy to be packaged. All greatly promote the development of aluminum electrolytic capacitance.   On the market, there are two types of aluminum electrolytic capacitors: organic semiconductor aluminum electrolytic capacitors (OS-CON) and polymer conductor aluminum electrolytic capacitors (PC-AC) (PC-CON).    The structure of an organic semiconductor aluminum electrolytic capacitor is similar to that of a liquid aluminum electrolytic capacitor; both are packaged in straight-pin and vertical configurations.   The difference is the cathode material of solid aluminum polymer electrolytic capacitor using the organic semiconductor extract, which can effectively solve the tough problems of electrolyte evaporation, leakage, flammability, and so on. Also, a solid aluminum polymer patch capacitor is a unique structure formed by combining the characteristics of aluminum electrolytic capacitance and tantalum capacitance.   Like liquid aluminum electrolytic capacitors, solid aluminum polymers are mostly in the form of patches. The film of polymer electrode with high conductivity is deposited on alumina as cathode, carbon, and silver as an extraction electrode, which is similar to the structure of solid tantalum electrolytic capacitance.     II. Solid State Capacitor Advantages   （1）With high stability, the solid aluminum electrolytic capacitor can work stably in a high-temperature environment, and improve the performance of the motherboard directly. At the same time, it is suitable for power filters because of its stable impedance in a wide temperature range, provides a stable and abundant power supply effectively, especially in overclocking.    Solid-state capacitors can work at high temperatures and maintain various electrical properties. The capacitance changes less than 15% in the whole temperature range, which is obviously superior to the liquid electrolytic capacitance. Meanwhile, the capacitance of solid-state electrolytic capacitor is independent of its working voltage, so it can work stably in the environment of voltage fluctuation.   （2）The solid-state aluminum electrolytic capacitor has an extremely long service life (over 50 years). It longer than the liquid aluminum electrolytic capacitance. And it will not be broken down, nor need to worry about liquid electrolyte drying and leakage affecting the stability of the motherboard. Solid-state electrolytes do not expand or even burn as liquid electrolytes do at high temperatures. Even if the temperature of the capacitor exceeds its limit, it just melts, which does not cause the capacitor metal shell to burst, so it is very safe.    The working temperature has a direct effect on the life of electrolytic capacitance. Advantages of its electrolyte make a longer service life than liquid electrolytic capacitor under different temperature conditions.   （3）Low ESR(Equivalent Series Resistance) and high mA rms are important indexes of capacitance. The lower the ESR, the faster the charge and discharge speed of capacitance. It directly affects the decoupling performance of the microprocessor power supply circuit, which is more obvious in high-frequency circuits. Therefore, it can be viewed the biggest difference between solid-state electrolytic capacitance and liquid capacitance.   Solid aluminum electrolytic capacitance with the lower ESR and energy dissipation under high power operation conditions can fully absorb the high amplitude voltage between the power lines in the circuit and prevent its interference to the system. When the CPU changes from a low power state to a full load state, the transient (generally less than 5 milliseconds) power required for this CPU switch comes from the CPU power supply circuit, at this moment, the high peak current can be output instantly by the high-speed charge-discharge characteristic of the solid-state capacitor, which can guarantee sufficient power supply and ensure the CPU to work stably.     III. Solid State Capacitor Types     According to the medium, capacitors can be divided into inorganic dielectric capacitors, organic dielectric capacitors, and electrolytic capacitors three categories.   1. Inorganic dielectric capacitors: including familiar ceramic capacitors and mica capacitors, we will often see ceramic capacitors on the CPU. Ceramic capacitors have excellent comprehensive properties and can be used in GHz-class UHF devices, such as CPU/GPU, thus its price is also very expensive.   2.Organic dielectric capacitors: such as thin-film capacitors, which are often used in loudspeakers with their precision, high temperature, and high-pressure resistance.   3. Electrolytic capacitors: known as aluminum capacitors. The traditional method of classifying electrolytic capacitors is based on anode materials, such as aluminum, tantalum, or niobium. However, this method of judging capacitance performance based on the anode is out of date. At present, the key to determine the performance of electrolytic capacitance lies not in the anode, but in the electrolytic, cathode. According to the classification of cathode materials, electrolytic capacitors can be divided into electrolyte, manganese dioxide, TCNQ organic semiconductors, solid polymer conductors, and so on.      IV. Breif Analysis of Advantages and Disadvantages of Solid Capacitors   The dielectric of liquid electrolytic capacitors is liquid electrolyte: liquid particles are very active at high temperatures and have a low boiling point relative to the internal pressure of the capacitor, making it easily explosible. The solid-state capacitance is made of polymer dielectric: at high temperatures, the particle growth and behavior of solid particles are lower than that of liquid electrolytes, and its boiling point will reach 350 degrees Celsius, making it almost impossible to burst.    The ESR of solid-state capacitance in high-frequency operation is shown to be very weak, and the conductivity is very fine. It has the properties of lowering impedance and producing less heat, which is the most obvious between 100KHz and 10MHz.   Traditional electrolytic capacitance is easily influenced by the operating environment's temperature and humidity, and it is less stable at high and low temperatures. The ESR of the solid capacitance can be as low as 0.0040.005 ohms between minus 55 and 105 degrees Celsius, but the electrolytic capacitance varies with temperature.   In terms of capacitance values, liquid capacitance would be lower than the indicated capacitance value below 20 degrees Celsius, and the lower the temperature, the lower the capacitance value. At minus 20 degrees Celsius, capacitance decreases by around 13%, and at minus 55 degrees Celsius, capacitance decreases by 37%. Since solid capacitance decreases by less than 5% at minus 55 degrees, solid state capacitors are guaranteed not to be harmed by lower temperatures. The low-frequency response of solid-state capacitance is not as good as electrolytic capacitance.     In other words, a motherboard with all-solid-state capacitance is not the most reasonable. Whether solid or electrolytic capacitors, their main function is to filter clutter, so long as the capacity and quality of capacitance can reach certain requirements, it can also ensure a stable operation. Solid-state capacitors at 105C have the same lifetime as electrolytic capacitors for 2000 hours.    When the temperature drops, their lives increase, but the solid-state capacitors increase even more. In general, the operational temperature of the capacitor is 70 degrees or less. In addition, the service life of solid-state capacitance can last 23 years, almost six times than the electrolytic capacitance. Compared with electrolytic capacitors, the capacity of electrolytic capacitors is much larger than that of solid capacitors at the same volume and voltage.     At present, solid capacitors are mostly used in the CPU power supply of computer motherboard, but the capacity redundancy is very little, it is necessary to improve the switching frequency of the part of the CPU power supply. Both solid and electrolytic capacitors will have the problem of capacity attenuation in the process of use. However, although the capacity of the circuit board with solid-state capacitance fluctuates slightly, the power supply will appear ripples, which will cause the CPU to work improperly.     Therefore, the lifetime of the solid-state capacitor is very high theoretically, but not in practice. Maintenance when using solid-state capacitor computer board: the power supply part of the CPU is often connected with multiple capacitors, so the solid-state capacitance will not have deformation, explosive slurry, leakage, etc. There is no way to determine which one is out of order basically. Therefore, in maintenance, one of them is often removed (no matter good or bad), and a large-capacity capacitor can be replaced (often with electrolytic capacitance). This method can usually solve the problem quickly.      In theory, the lifetime of the solid-state capacitor is very long, but there will still be a lot of faults in the process of practical use. At present, it seems that most motherboards with overclocking as the selling point put forward by many manufacturers will use solid-state capacitors. But it is not the capacitance that determines the performance of the CPU. The design of the circuit, the development of BIOS, the quality of the CPU itself, and the heat dissipation measures may determine the success or failure of the CPU.   FAQ   1. What is a solid state capacitor? The full name of a solid capacitor is a conductive polymer aluminum electrolytic capacitor, also called a polymer aluminum capacitor. It is currently the highest level of capacitor products. The dielectric material of the solid capacitor is a functional conductive polymer, which can greatly improve the product.   2. Are Solid Capacitors better? Solid capacitors have a higher tolerance not only for higher temperatures, but they also perform better with higher frequencies and higher current than electrolytic capacitors. ... Because there is less impedance at higher frequencies, solid capacitors are more stable and generate less heat than electrolytic capacitors.   3. How do you read a solid state capacitor? If you have a capacitor that has nothing other than a three-digit number printed on it, the third digit represents the number of zeros to add to the end of the first two digits. The resulting number is the capacitance in pF. For example, 101 represents 100 pF: the digits 10 followed by one additional zero.   4. What do you need to know about solid state capacitors? Solid-state capacitors have already gone down the altar. Many common electronic and digital products use these products in large quantities. The solid-state capacitors are similar to the common aluminum electrolytic capacitors, some are replaceable, and there is a solid capacitor, sheet, for Replace the common tantalum capacitor.   5. Which is the best electrolytic capacitor for motherboard? Solid aluminum electrolytic capacitors can directly improve the performance of the motherboard. At the same time, it is suitable for power supply filtering due to its stable impedance over a wide temperature range. It can effectively provide a stable and abundant power supply, which is especially important in overclocking.   6. How do you read a solid state capacitor? If you have a capacitor that has nothing other than a three-digit number printed on it, the third digit represents the number of zeros to add to the end of the first two digits. The resulting number is the capacitance in pF. For example, 101 represents 100 pF: the digits 10 followed by one additional zero.   7. What is the average lifespan of a capacitor? Design lifetime at rated temperature. Manufacturers of electrolytic capacitors specify the design lifetime at the maximum rated ambient temperature, usually 105°C. This design lifetime can vary from as little as 1,000 hours to 10,000 hours or more.   8. What metals are capacitors made of? There are three different anode metals in use for electrolytic capacitors: Aluminum electrolytic capacitors use a high-purity etched aluminium foil with aluminium oxide as dielectric. Tantalum electrolytic capacitors use a sintered pellet (“slug”) of high-purity tantalum powder with tantalum pentoxide as dielectric.   9. When should you use a capacitor? Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass. In analog filter networks, they smooth the output of power supplies.   10. How do I choose the right size capacitor? You mainly need to look at 2 values: the voltage and the capacity -both are written on most capacitors-. For example, if you are going to charge a capacitor with 24V, you need to make sure your capacitor will support that voltage; so you'll need a capacitor for at least 25V (plus error margin).       You May Also Like Operational Amplifier(OP Amp) Tutorial Instructions of Common problems in the Application of Inverter About Operational Amplifier LM358: 24 Classical Circuits DIY Community:  DIY Capacitor Flux Capacitor - Back TO The Future

  Op-amp is short for operational amplifier. In practical circuits, they are usually combined with a feedback network to form some kind of functional module. It was named "operational amplifier" because it was used in the early days of analog computers to realize mathematical operations, and the name has been continued to this day. An operational amplifier is a circuit unit named from the point of view of function, and can be implemented by discrete devices or in semiconductor chips. With the development of semiconductor technology, the majority of op amps exist today in the form of a single chip. Nowadays, there is a wide variety of op amps, which are widely used in almost all industries. What is an operational amplifier? Catalog   Working principle of operational amplifier  Why is operational amplifier called op amp? Types of op amp Features of op amp FAQ Working principle of operational amplifier  When an operational amplifier is used, its output is connected to its inverTIng input node to form a negative feedback configuration—negaTIve. The reason is that the voltage gain of the operational amplifier is very large, ranging from hundreds to tens of thousands of times, the use of negative feedback to ensure the stable operation of the circuit. But that doesn't mean the operational amplifiers can't be connected to the positive feedback. On the contrary, in many systems that need to generate oscillatory signals, OP Amp with positive feedback configuration is a common component. Operational amolifier schematic diagram    Why is operational amplifier called op amp? In an actual circuit, the feedback network is usually combined to form a certain functional module. Since it was used in analogue computer to realize mathematical operation, it is named "operational amplifier", which continues to this day. Operational amplifier is a circuit unit based on its function, which can be implemented by discrete devices or semiconductor chips. With the development of semiconductor technology, the vast majority of operational amplifiers are in the form of single chip. Nowadays, there are many kinds of operational amplifiers, which are widely used in almost all industries. History of operational amplifier    Summing amplifier In 1941, the first operational amplifier composed of vacuum tubes was invented by Karl D. Swartzel Jr. Of Bell Labs and got the American patent 2,401,779, named “Summing Amplifier”. Model K2-W In 1952, model K2-W, the first operational amplifier with vacuum tube was sold by George A. Philbrick Researches (GAP/R) in the market. μA702 In 1963, the first operational amplifier in the form of a single IC chip was the μA702 designed by Fairchild Senmiconductors's Bob Widlar, and it was introduced after modification in 1965 named μA709.  μA741 In 1968, Fairchild Semiconductor Inc. Introduced the μA741 still in production, it is one of the most successful operational amplifiers of all the time and one of the very few oldest IC models.   - In 1941, the first operational amplifier composed of vacuum tubes was invented by Karl D. Swartzel Jr. Of Bell Labs and got the American patent 2,401,779, named “Summing Amplifier”. - In 1952, model K2-W, the first operational amplifier with vacuum tube was sold by George A. Philbrick Researches (GAP/R) in the market. - In 1963, the first operational amplifier in the form of a single IC chip was the μA702 designed by Fairchild Senmiconductors's Bob Widlar, and it was introduced after modification in 1965 named μA709.  - In 1968, Fairchild Semiconductor Inc. Introduced the μA741 still in production, it is one of the most successful operational amplifiers of all the time and one of the very few oldest IC models.   Types of op amp - General type: Its performance parameters are suitable for general use (low frequency and slow signal change), such as 741A, LM358 (double OP Amp), LM324 and LF356  with FET as input stage. - High-Z type:The characteristic of this kind of amplifier is that the input impedance of differential mode is very high and the input bias current is very small. The main measure to achieve these targets is to make use of the high input impedance of FET, but the input offset voltage of this kind of operational amplifier is larger. Such operational amplifier have LF356, LF355, LF347, CA3130, CA3140, etc. - Low-temperature drift type:In precision instruments, weak signal detection and other automatic control instruments, the bias voltage of operational amplifier is small and does not change with the temperature. The low temperature drift operation amplifier is designed for this purpose. At present, the commonly used operational amplifier has OP07, OP27, OP37, AD508 and ICL7650 composed of MOSFET device and so on. - High slew-rate type:In fast A/D converter, D/A inverter and video amplifiers, the conversion rate of the operational amplifier must be high, and the BWG of the unit gain bandwidth must be large enough. Common operational amplifier has LM318, 175A and so on. - Low -consumption type: Due to the wide application of portable instruments, low power supply and low power consumption must be used. Commonly used low-power operational amplifier has TL-022C,TL-160C and so on. - High voltage and power type:The output voltage of operational amplifier is mainly limited by power supply. In ordinary operational amplifier, the maximum output voltage is only dozens of volts and the output current is only dozens of Ma. In order to increase the output voltage and current, the auxiliary circuit must be added to the external circuit of the operational amplifier. High-voltage and high-power operational amplifier can output high voltage and high current without any additional circuit.   Features of op amp The input resistance is very high, the output resistance is very small, the voltage magnification is very large, and the zero drift is very small. Characteristics of ideal operational Amplifier in Linear region - Virtual Ground: When the operational amplifier is in a linear state, the potential of the inverse input is zero. - Virtual Short Circuit: When the operational amplifier is in a linear state, the two input terminals can be regarded as equipotential, which is called virtual short circuit. But both sides are not real short circuit. - Virtual Open Circuit: When the operational amplifier is in a linear state, two input terminals can be regarded as equivalent open circuit, which is called virtual open circuit. Obviously, it doesn’t break the two inputs actually.   FAQ   1. What is an op amp used for? What is an Operational Amplifier (Op-amp)? An operational amplifier is an integrated circuit that can amplify weak electric signals. An operational amplifier has two input pins and one output pin. Its basic role is to amplify and output the voltage difference between the two input pins.   2. What is op amp in electronics? An operational amplifier (op amp) is an analog circuit block that takes a differential voltage input and produces a single-ended voltage output. ... The inverting input is denoted with a minus (-) sign, and the non-inverting input uses a positive (+) sign.   3. How do op amps work? An operational amplifier only responds to the difference between the voltages on its two input terminals, known commonly as the “Differential Input Voltage” and not to their common potential. Then if the same voltage potential is applied to both terminals the resultant output will be zero.   4. What is a 741 op amp used for? The most common Op-Amp is the 741 and it is used in many circuits. The OP AMP is a 'Linear Amplifier' with an amazing variety of uses. Its main purpose is to amplify (increase) a weak signal - a little like a Darlington Pair. The OP-AMP has two inputs, INVERTING ( - ) and NON-INVERTING (+), and one output at pin 6.   5. What are the characteristics of op amp? -Infinite open-loop gain G = vout / v. in -Infinite input impedance Rin, and so zero input current. -Zero input offset voltage. -Infinite output voltage range. -Infinite bandwidth with zero phase shift and infinite slew rate. -Zero output impedance R. out -Zero noise. -Infinite common-mode rejection ratio (CMRR)   6. Where are op amps used? Op-amps are linear devices that are ideal for DC amplification and are used often in signal conditioning, filtering or other mathematical operations (add, subtract, integration and d3.   7. What is operational amplifier and its types? An operational amplifier (op amp) is an analog circuit block that takes a differential voltage input and produces a single-ended voltage output. Op amps usually have three terminals: two high-impedance inputs and a low-impedance output port.   8. Why is it called operational amplifier? Op-amp stands for operational amplifier. ... Originally, op-amps were so named because they were used to model the basic mathematical operations of addition, subtraction, integration, differentiation, etc. in electronic analog computers. In this sense a true operational amplifier is an ideal circuit element.   9. What is the difference between amplifier and operational amplifier? Amplifiers can be either electronic or mechanical in common definition whereas operational amplifiers are electronic amplifiers. Amplifiers, in general, have a limited capability of amplifying DC signals but all op-amps are capable of amplifying DC signals.   10. What is the main function of operational amplifier? An operational amplifier is an integrated circuit that can amplify weak electric signals. An operational amplifier has two input pins and one output pin. Its basic role is to amplify and output the voltage difference between the two input pins.   11. What are the advantages of operational amplifier? Advantages:  1. increased circuit stability 2. increased input impedance  3. decreased output impedance  4. increased frequency bandwidth at constant gain.   12. What are op amps used for in real life? Op amps are widely used in amplifiers oscillators, filters, comparators, integrators and differentiation,voltage regulator, current regulator. Non linear applications include precision rectified log amplifier . It is also used in analog to digital and digital to analog converter.   13. Where are operational amplifiers used? Operational amplifiers are linear devices that have all the properties required for nearly ideal DC amplification and are therefore used extensively in signal conditioning, filtering or to perform mathematical operations such as add, subtract, integration and differentiation.   14. What is an ideal operational amplifier? Operational amplifier: The ideal op amp is an amplifier with infinite input impedance, infinite open-loop gain, zero output impedance, infinite bandwidth, and zero noise. It has positive and negative inputs which allow circuits that use feedback to achieve a wide range of functions.   15. Why does an operational amplifier need a power supply? Operational amplifiers have two power supply rails because they usually need to swing bipolar - output voltages that go either positive or negative in response to the normal range of input signals. ... Without the dual supplies the output signal would clip at the ground potential.   16. How op-amp can be used as a differentiator? An op-amp differentiator is an inverting amplifier, which uses a capacitor in series with the input voltage. ... Differentiators have frequency limitations while operating on sine wave inputs; the circuit attenuates all low frequency signal components and allows only high frequency components at the output.   17. Is an op amp a transistor? Well for starters, an op amp is simply a combination of transistors, so by varying the transistor you can get different properties. One thing to also remember is that op amps are class A amplifiers which basically means that they are always on and therefore drawing power which can be undesirable.   18. Why is op amp a versatile device? Op Amps or operational amplifiers, are fundamental building blocks in electronic design, mainly because these analog integrated circuits (ICs) are very versatile. ... The term “differential amplifier,” for instance, simply means that the op amp will try to amplify any difference between the signals.   19. Does op amp need ground? An Op Amp inverting input (-) is at zero potential (A virtual ground), even though it does not have a galvanic connection to ground.   20. What is the difference between real ground and virtual ground? Real ground is when a terminal is connected physically to the ground or earth. where as virtual ground is a concept used in Op-Amps in which a node is assumed to have the potential that of the ground terminal.  

This article mainly tells about what's an op amp, and then briefly introduce LM358 about its features and parameters, the last we present you the 24 classical circuits of LM358.     Catalog   I. What is an Op Amp? II. LM358 Introduction      2.1 What is LM358?      2.2 LM358 Features      2.3 LM358 Parameters III. 24 Classic Circuits of LM358 FAQ   I. What is an Op Amp? This is a tutorial video introducing what's an opearational amplifier in details.   II. LM358 Introduction   2.1 What is LM358? The LM358 includes two independent, high gain, internal-frequency compensated dual operational amplifiers that are suitable for single power sources with a wide range of voltages, as well as dual-power operation modes. Under recommended operating conditions: the power supply current is independent of the power supply voltage. Its applying range includes sensor amplifiers, DC gain modules, audio amplifiers, industrial control, DC gain components, and all other situations where operational amplifiers can be used with a single power supply.   The LM358 has plug-in type and the patch type packaging which are the plastic package with double-row 8 lead wires.     2.2 LM358 Features       2.3 LM358 Parameters Input bias current 45 nA Input offset current 50 nA Input offset voltage 2.9mV Power suppression ratio (100dB) Common-mode suppression ratio (80dB) Input common-mode voltage maximum VCC about 1.5 V   III. 24 Classic Circuits of LM358   Schematic diagrams are as shown as following:  Figure 1. DIP Plastic Pin Diagram Figure 2. Circular Metal Shell Packaging Pin Diagram Figure 3. Internal Circuit Schematic Diagram Figure 4. DC Coupled Low Pass RC Active Filter Figure 5. LED Driver Figure 6. TTL Drive Circuit Figure 7. RC Bandpass Filter (BPF) Figure 8. Squarewave Oscillator Figure 9. Hysteresis Comparator Figure 10. Bandpass Filter (BPF) Figure 11. Lamp Driver Figure 12. Current Monitor Figure 13. Low Drift Peak Value Detector Figure 14. Voltage Follower Figure 15. Power Amplifier Peripheral Circuit Figure 16. Voltage Controlled Oscillator (VCO) Figure 17. Fixed Current Source Figure 18. Pulser Figure 19. AC Coupled Inverting Amplifier Figure 20. AC Coupled Non-Inverting Amplifier Figure 21. Adjustable Gain Instrument Amplifier Figure 22. DC Amplifier Figure 23. Pulser Figure 24. Bridge Current Amplifier FAQ   1. What is lm358 op amp? LM358 is a dual op-amp IC integrated with two op-amps powered by a common power supply. It can be considered as one half of LM324 Quad op-amp which contains four op-amps with common power supply. The differential input voltage range can be equal to that of power supply voltage.   2. What is lm358 used for? LM358 can be used as transducer amplifier, DC gain block etc. It has large dc voltage gain of 100dB. This IC can be operated on wide range of power supply from 3V to 32V for single power supply or from ±1.5V to ±16V for dual power supply and it also support large output voltage swing.   3. How does an lm358 work? IC LM358– LM358 consists of two independent, high gain operational amplifiers in one package. Important feature of this IC is that we do not require independent power supply for working of each comparator for wide range of power supply. LM358 can be used as transducer amplifier, DC gain block etc.   4. How do I know if my lm358 op amp is broken? Measure the DC voltage at the +input. then measure the DC voltage at the output. if the results are significantly different, the opamp is most likely shot. if they are the same, the opamp is most likely ok and the problem is something else.   5. What is the difference between lm386 and lm358？ The LM386 is a complete audio power amplifier, the LM358 is a dual operational amplifier. When using the LM358 e.g. as a pre-amplifier, you will have to supply a separate power amplifier.   6. How to import lm358 into LTspice? 1. Download model file and unzip.2. Place .cir file in same folder as schematic.3. Place "opamp2" symbol on schematic.4. Change "opamp2" value to LMX58_LM2904.5. Place directive on schematic ". lib LMx58_LM2904. CIR" without quotes.   7. How many comparators are in LM358? 2 comparator. In this tutorial LM358 IC is used. It has got 2 comparator.   8. What is the difference between LM358 and LM741? Two commonly used opamp are LM741 & LM358. Difference between LM358 & LM741 is, LM358 is newer and have two OP-AMP on chip while in 741 only one OP-AMP is present. Both the IC's have 8 pins.   9. Why does an op amp require both positive and negative supply voltages? Without the dual supplies the output signal would clip at the ground potential. Operational amplifiers have two power supply rails because they usually need to swing bipolar - output voltages that go either positive or negative in response to the normal range of input signals.   10. Does op amp need ground? An Op Amp inverting input (-) is at zero potential (A virtual ground), even though it does not have a galvanic connection to ground. You May Also Like Rectifiers and Filters Notes A Load Insensitive High-Power Balanced Power Amplifier Discussion on the influencing factors of clock in FPGA design Brief introduction to the Application of some IC chips in Maxim Integrated DIY Community: Let's make amplifier Rechargable Pokect Sized Amplifier Portable - Mini Amplifier Speaker

    Circuit protection is a frequently discussed topic, and the various types of circuit protection differ due to the various problems in the circuit. Short-circuit, overload, grounding, and lightning strikes are the most common faults in power supply systems. To ensure the safe and dependable operation of the power supply system, protection devices must be installed to monitor the working conditions of the power supply system, detect faults in time, and cut off the power supply of the faulty equipment, preventing the accident from spreading. In general, the protection circuit is made up of various relays, signal indicating devices, and other components. This blog provides an in-depth discussion on several circuit protections. Below is an introduction video about short circuit protection. DIY Short Circuit (Overcurrent) Protection   Catalog   I Introduction to circuit protection II Switching power principle and characteristics      2.1 Operational principle of switching power      2.2 Characteristic of switching power III DC Switching power supply protection      3.1 Overcurrent protection circuit      3.2 Overvoltage protection circuit      3.3 Soft start protection circuit        3.4 Overheat protection circuit IV Conclusion FAQ   I Introdcution to circuit protection The operation of electronic equipment can not be separated from electricity, so DC switching power supply which can control the electricity is playing a more and more important role. And it has entered various fields of electronics and electrical equipment: SPC exchange, communication, electronic testing equipment power supply and controlling equipment power supply, which are widely used DC switching power supply.  Meanwhile, with the development of many high-tech technologies, including high-frequency switching technology, soft-switching technology, power factor correction technology, synchronous rectifier technology, intelligent technology, surface installation technology, etc., switching power supply technology is constantly innovating. This provides a wide range of development for DC switching power supply.  DC current diagram   But the circuit is complex to control in the switching power supply, the transistor and the integrated device have poor resistance to electricity and thermal shock, which brings great inconvenience to the user in the process of using. In order to protect the safety of switching power supply itself and load, the overheat protection, over-current protection, over-voltage protection and soft start protection circuit are designed according to the principle and characteristics of DC switching power supply.   II Switching power principle and characteristics 2.1 Operational principle of switching power DC switching power supply is composed of input part, power conversion part, output part and control part. The power conversion part is the core of the switching power supply. It performs conversion which needed for the output on the high-frequency and unstable DC. It is mainly composed of switching transistor and high frequency transformer. Figure 1. DC Switching power supply principle Figure 1 shows the schematic diagram and equivalent schematic block diagram of DC switching power supply, which is composed of full wave rectifier, switching tube V, excitation signal, fly-wheel diode Vp, energy storage inductance and filter capacitance C. In fact, the core part of DC switching power supply is a DC transformer. 2.2 Characteristic of switching power   In order to meet the needs of users, the world's major switching power supply manufacturers are committed to the simultaneous development of new and highly intelligent components, especially by reducing the loss of the secondary rectifier. In order to improve the magnetic properties under high frequency and high magnetic flux density, power ferrite (Mn-Zn) materials have been developed. At the same time, the application of SMT technology in the field of switching power supplies has also made considerable progress. The components are arranged on both sides of the circuit board to ensure that the switching power supply is light, small and thin. Therefore, high frequency, high reliability, low power consumption, low noise, anti-interference and modularization are the development trends of DC switching power supplies. However, DC switching power supplies also have disadvantages. The DC switching power supply switch has serious interference, and its ability to adapt to harsh environments and sudden failures is weak. There is still a certain gap in microelectronics technology in developing countries. Specifically, the production technology of resistors and capacitors and the technology of magnetic materials are compared with those of some technologically advanced countries. Therefore, the manufacture of DC switching power supplies is very difficult. In most parts of the world, maintenance is difficult and the cost is high. III DC Switching power supply protection Based on the characteristics of DC switching power supply and the actual electrical condition, in order to make DC switching power supply work safely and reliably in bad environment and sudden fault, this paper designs a variety of protection circuits according to different conditions. 3.1 Overcurrent protection circuit   Figure 2. Input Overcurrent protection circuit In DC switching power supply circuit, in order to avoid short circuit and overflow damage to protect the regulator tube in the circuit, the basic method is that, when the output current exceeds a certain value, the regulator tube is in the reverse bias state, thus the circuit current is cut off automatically. As shown in Fig. 2, the over-current protection circuit consists of transistor BG2 and divider resistor R4, R5. When the circuit works normally, the base potential of BG2 is lower than that of emitter through the partial voltage interaction between R4 and R5, and the emitter junction bears reverse voltage. So the BG2 is in the cutoff state (equivalent to open circuit), which is used to stabilize the voltage. But the voltage stabilizing circuit has no effect. When the circuit is short circuit, the output voltage is zero and the emitter of BG2 is equivalent to grounding, then the BG2 is in the state of saturation conduction (equivalent to short circuit), so that the regulator tube BG1 base and emitter are close to short circuit, and in the cut-off state, the circuit current is cut off to achieve the purpose of protection.   3.2 Overvoltage protection circuit The overvoltage protection of switching regulator in DC switching power supply includes input overvoltage protection and output overvoltage protection. If the voltage of the unstabilized DC power supply (such as batteries and rectifiers) used by the switching regulator is too high, it will cause the switching regulator to fail to work properly and even damage the internal devices. Therefore, it is necessary to use the input overvoltage protection circuit in the switching power supply. Fig. 3 is a protection circuit composed of transistors and relays, in which the voltage of the input DC power supply is higher than the breakdown voltage of the zener diode, at this condition, current flows through resistor R, making diode T conducts. Following these electrical actions, relay operates and common closed contact disconnected, inputting current. The polarity protection circuit of the input power supply can be combined with the input overvoltage protection to form the polarity protection identification and overvoltage protection circuit. Figure 3. Input overvoltage protection circuit 3.3 Soft start protection circuit The circuit of switching power supply is complex, the input end of switching regulator is usually connected with small inductance and large-capacitance input filter. At start-up instant, the filter capacitor flows through a large surge current that can be several times the normal input current. Such a large surge current melts the contacts of the normal power switch or the relay and melts the input fuse. In addition, surge current can also damage capacitors, shorten their life, cause premature damage. To this end, a current-limiting resistance should be connected in the circuit, through this current-limiting resistance to charge the capacitor. In order not to consume too much power by the current limiting resistance, and avoid affecting the normal operation of the switching regulator, therefore a relay is used to connect it automatically after the transient process is finished, which makes the DC power supply directly to the switching regulator. This is called the "soft start" circuit of DC switching power supply. Figure 4. Soft start-up protection circuit When the power supply is switched on, capacitor C is charged by input voltage through rectifier bridge (D1 ~ D4) and current-limiting resistance R1 to limit the surge current. The inverter works normally when the capacitor C is charged to about 80% rated voltage. The trigger signal of thyristor is generated by auxiliary winding of main transformer, which makes thyristor switch on and short circuit current-limiting resistance R1, and the switching power supply is in normal operation state. In order to improve the accuracy of the delay time and prevent the relay operation from shaking and oscillating. The delay circuit can replace the RC delay circuit by the circuit shown in figure 4(b). 3.4 Overheat protection circuit The high integration and light weight of switching regulator in DC switching power supply greatly increase the power density per unit volume, so if the internal components of the power supply do not have a corresponding increase in the temperature of its working environment, it will inevitably make the circuit performance damaged and components life service shortened prematurely. Therefore, overheating protection circuit should be installed in high power DC switching power supply. Figure 5. Overtemperature protection circuit In this paper, the temperature relay is used to detect the internal temperature of the power supply device. When the inside of the power supply device is overheated, the temperature relay operates, which makes the alarm circuit of the whole machine in the state of alarm and realizes the protection of the overheating of the power supply.  As shown in Fig. 5 (a), the P type control gate thermal thyristor is placed near the power switch transistor in the protection circuit. According to the characteristics of the TT102 (the on-on temperature of the device is determined by the Rr value, the larger the Rr is, The lower the conduction temperature), when the temperature of the power tube or the temperature inside the device exceeds the allowable value, the thermal thyristor is switched on and the LED is lighting to give an alarm. If cooperate with photoelectric coupler which can make whole machine alarm circuit operation, protecting switch power supply.  The circuit can also be designed as shown in Fig. 5 (b) to protect the power transistor from overheating. The base current of the switching transister is bypassed by the TT201 of the N type control gate thermal thyristor, and the switch tube is cut off, also the collector current is cut off, and the overheating is prevented. IV Conclusion This blog mainly discusses various protection methods of internal devices in DC switching power supply, and introduces some concrete circuits. For a given DC switching power supply, it is very important for the security and reliability of the power supply device whether the protection circuit is perfect and set up to work necessarily. Because the protection scheme and circuit structure of switching power supply are diverse, reasonable protection scheme and circuit structure should be chosen for specific power supply devices. In practical application, several protection methods are usually used to form a perfect protection system to ensure the normal operation of DC switching power supply.   FAQ   1. What is the purpose of circuit protection? The basic goals of circuit protection are to 1) localize and isolate the condition or fault and 2) prevent and minimize any unnecessary power loss. There are several types of abnormal conditions that may occur throughout a building's life, in which an electrical system must be designed to correct or overcome.   2. What protective devices are used in circuits? Fuses, MCBs, RCDs, and RCBOs are all devices used to protect users and equipment from fault conditions in an electrical circuit by isolating the electrical supply.   3. How do you protect a circuit design? The most basic device is a fuse, a type of low resistance resistor that acts as a sacrificial device to provide over current protection, of either the load or source circuit. A fuse protects the circuit, but once it's utilized, it's kaput.   4. What are the two main circuit protection devices? The two types of circuit protection devices discussed in this chapter are fuses and circuit breakers. A fuse is the simplest circuit protection device. It derives its name from the Latin word "fusus," meaning "to melt." Fuses have been used almost from the beginning of the use of electricity.   5. What is a DC switching power supply? A Switching DC power supply (also known as switch mode power supply) regulates the output voltage through a process called pulse width modulation (PWM). The PWM process generates some high frequency noise, but enables the switching power supplies to be built with very high power efficiency and small form factor.   6. What are the differences between linear DC power supply and switching power supply? Linear power supplies deliver DC by passing the primary AC voltage through a transformer and then filtering it to remove the AC component. Switching power supplies feature higher efficiencies, lighter weight, longer hold up times, and the ability to handle wider input voltage ranges.   7. Can I use a switching power supply to drive a DC motor? A simple unregulated analog power supply may be easier and be able to supply the large starting under load current more that the switching one. DC motors are not too fussy about the supply, and will usually run quite well on unfiltered DC.   8. Do I need a switching power supply? The switching power supply implies higher efficiency due to the high switching frequency, enabling it to use a smaller, less-costly high-frequency transformer as well as lighter, less-costly filter components. Switching power supplies contain more overall components, therefore are usually more expensive.   9. What are the 3 types of power supply? There are three subsets of regulated power supplies: linear, switched, and battery-based. Of the three basic regulated power supply designs, linear is the least complicated system, but switched and battery power have their advantages.   10. What is a switching mode power supply used for? Switched-mode power supplies are used to power a wide variety of equipment such as computers, sensitive electronics, battery-operated devices and other equipment requiring high efficiency.    

The insulated gate bipolar transistor (hereinafter referred to as IGBT) is a composite device of MOSFET and GTR. Thus it has the advantages of MOSFET and GTR, it is an ideal switch device to replace GTR, which is widely used at present with its ability to turn off, and it’s also widely used in all kinds of solid-state power supply.     Catalog   I. What is IGBT? II. The Driving Requirement of IGBT III. The Overcurrent Protection Analysis of IGBT IV. Simulation and Experiment FAQ   I. What is IGBT?   The insulated gate bipolar transistor (hereinafter referred to as IGBT) is a composite device of MOSFET and GTR. Thus it has the advantages of MOSFET, including fast operation speed, high switching frequency, high input impedance, simple drive circuit, and good thermal temperature; it also contains the advantages of GTR, like large current-carrying capacity and high blocking voltage. It is an ideal switch device to replace GTR, which is widely used at present with its ability to turn off and is also widely used in all kinds of solid-state power supply.   And it requires a reasonable drive circuit, but its improper control may cause damage, such as IGBT damage due to overcurrent, and affects the performance of the whole machine. In a word, the drive circuit is very important to IGBT. So this paper mainly discusses the driving and short-circuit protection of IGBT, based on the analysis of its working principle, then designs and simulates the overcurrent protection of the drive circuit.     Electronic Basics #28: IGBT and when to use them     II. The Driving Requirement of IGBT   Driving Requirement IGBT is a voltage-type control device. To make IGBT turn on and off safely and reliably, the driving circuit must meet the following conditions.  And the gate capacitance of IGBT is much larger than that of MOSFET. To increase the switching speed, it is necessary to have a suitable gate bias voltage and gate series resistance.   Gate Voltage In any case, the gate drive voltage in the open state can not exceed the limited value (generally 20V) given by the parameter table, and the optimal gate forward-bias voltage is 15 V ±1.5V. This value is sufficient to allow IGBT to reach saturation and then getting conduction, which can minimize the conduction loss. In the case of gate voltage is cutting off with the value of zero, to reduce the turn-off time and improve the withstand voltage and anti-interference ability of IGBT, a reverse voltage of -5 ~ -15 V can be added between the gate and the source electrode when the IGBT is in a blocking state.   Gate Series Resistance Core The selection of appropriate gate series resistance (RG) is very important for the drive of IGBT. The effect of RG on switching loss is shown in Fig.1. Fig. 1 The Effect of RG on Switching Loss It is the dynamic current of charging and discharging the input capacitance rather than the DC current that is required in a static state, and the input impedance of IGBT is up to 109 ~ 1011. In this case, the DC gain can reach 108 ~ 109, almost without any power consumption.   To decrease the steepness of the front and rear edges of the control pulse, prevent oscillation and reduce the voltage tip pulse with a large IGBT collector, it is necessary to add a gate series resistor RG. When the RG increases, the on-off time will prolong and the energy consumption of the IGBT will increase; in turn, the RG reduces, the di/dt will increase and may damage IGBT.   Thus, according to the current capacity and voltage rating, and switching frequency of IGBT, it is necessary to select a suitable RG, usually from dozens of ohms to hundreds of ohms. To get a more specific value of RG, it is suggested to refer to the device manual. Fig.2 Main Circuit of Inverter Power Supply   Requirements for Driving Power The switching process of IGBT consumes a certain amount of power from the driving power supply. The difference between the gate forward bias voltage and the reverse bias voltage is the △VGE; working frequency is f, the gate capacitance is CGE; and the minimum peak current of the power supply is:     Overcurrent Protection for IGBT The overcurrent protection of IGBT is limiting the short-circuit current and its I-V track to the short circuit safe working area when the device overflows, and the IGBT is turned off before the device is damaged to avoid the damage of the switch tube. When the upper and lower arms conducting, the power supply voltage is almost all added to the two ends of the switch, at this time, the larger the short circuit current is, the smaller the saturation voltage drop will be, during this time, the device would be damaged due to the large current.     III. The Overcurrent Protection Analysis of IGBT   Based on the above analysis, an IGBT drive circuit which contains isolated optocoupler and over-current protection has been put forward in this article, as shown in Fig.3. Fig.3 The Drive and Overcurrent Protection Circuit of IGBT  In Fig.3, the high-speed optocoupler 6N137 realizes the electrical isolation of the input and output signals, which is suitable for high-frequency applications. The main drive circuit adopts push-pull output mode, which effectively reduces the output impedance of the drive circuit, improves the driving ability, and makes it suitable for the drive of high power IGBT.   The over-current protection circuit uses the principle of desaturation of the collector. When an over-current occurs, the IGBT will be turn off. The V1, V3and V4 constitute the driving pulse amplifier circuit; V1 and R5 constitute an emitter follower. The emitter follower provides a fast current source, which reduces the turn-off time. Using the collector desaturation principle, D1, R6, R7, and V2 form a short-circuit signal detection circuit. D1 is a fast recovery diode, to prevent the high voltage on the collector from running into the driving circuit when IGBT is turned off.   In order to prevent the power device from being misled by static electricity, bidirectional voltage regulators D3 and D4 are connected in parallel between the gate sources.   Normal When the control circuit sends a high-level signal, the optocoupler 6N137 turns on, V1, V2 turns off, V3 turns on and V4 turns off. And the drive circuit provides IGBT a driving voltage of +15V to turn it on. When the control circuit sends a low level signal, the optocoupler 6N137 turns off, V2 and V3 conduct, and the drive circuit provides a voltage of -5v to IBGT, making IGBT shut down.   Overcurrent When a short-circuit fault exists, the voltage of 15V is almost all added to the IGBT. At this time, the voltage of V2 cuts off in the short circuit detection circuit, and the electric potential of point A depends on the partial voltage of D1, R6, R7, and VCES.  When the main circuit works normally and the IGBT is on, the A point is kept low, which is lower than the B point potential. All A1 output low level, this time V5 cuts off, and the C point is high level.   So when operating normally, the input to the optocoupler 6N137 is always consistent with the output. When overcurrent occurs, the IGBT collector is desaturated, A point potential rises, when it is higher than B potential ( the setting potential), that is, when the current exceeds the designed fixed value, the A1 overturns and outputs a high level, meanwhile, V5 is switched on, thereby making C in a low potential state. The input signal to the optocoupler 6N137 is always low level regardless of whether the control circuit is sent to a high level or a low level to turn off the power tube. Thus, over-current protection is achieved until the circuit is troubleshot and then restarted.   Fig. 4 Strong Driving Circuit of IGBT with Short-Circuit Protection   IV. Simulation and Experiment   Input to the drive circuit with a high level of 15V and a low level of -5V square wave signal. The output waveform of IGBT is shown in Fig.5  Fig.5 IGBT Output Signal According to the above principle and analysis, the actual output waveform of the circuit is shown in Fig.6  Fig.6 Actual Circuit Output Waveform Conclusion (1) Providing -5V and +15V driving voltage for IGBT to ensure IGBT's turn on and off. (2) Having over-current protection to prevent the IGBT from being damaged when the current is overcurrent. (3) Using in a wide range because the circuit can dynamically adjust the maximum current according to the load. (4) Adopting discrete components as the driving circuits to reduce the cost of the whole system.     FAQ   1. How does an insulated gate bipolar transistor work? The IGBT combines the simple gate-drive characteristics of power MOSFETs with the high-current and low-saturation-voltage capability of bipolar transistors. The IGBT combines an isolated-gate FET for the control input and a bipolar power transistor as a switch in a single device.   2. Which insulated gate bipolar transistor? IGBTs are widely used as switching devices in the inverter circuit (for DC-to-AC conversion) for driving small to large motors. IGBTs for inverter applications are used in home appliances such as air conditioners and refrigerators, industrial motors, and automotive main motor controllers to improve their efficiency.   3. How do I trigger IGBT?   An IGBT is simply switched “ON” and “OFF” by triggering and disabling its Gate terminal. A constant +Ve voltage i/p signal across the 'G' and the 'E' will retain the device in its “ON” state, while deduction of the i/p signal will cause it to turn “OFF” like BJT or MOSFET.   4. Why use an IGBT instead of a Mosfet? The main advantages of IGBT over a Power MOSFET and a BJT are: 1. It has a very low on-state voltage drop due to conductivity modulation and has superior on-state current density. So smaller chip size is possible and the cost can be reduced.   5. Why IGBT is used an inverter? The Insulated Gate Bipolar Transistor (IGBT) is used in VFD inverter modules as the preferred electronic power switch for the following reasons. ... The IGBT has a fast switching speed. This minimises switching losses and allows for high switching frequencies which is good for motor harmonic and noise reduction.   6. What is difference between IGBT and SCR? SCR is a silicon control rectifier and igbt is a insulated gate bipolar transistor. ... scr has anode ,cathode and gate and igbt has base ,emitter, gate ,and collector. In the both devices gate terminal is used for triggering. Scr has only one insultive layer but igbt has 2 insulated silicon layers.   7. What is IGBT principle? IGBT Principle of Operation：IGBT requires only a small voltage to maintain conduction in the device unlike in BJT. The IGBT is a unidirectional device, that is, it can only switch ON in the forward direction. This means current flows from the collector to the emitter unlike in MOSFETs, which are bi-directional.   8. What causes IGBT failure? The failure modes for the IGBT are in the form of degradation of certain key electrical parameters (e.g., leakage current, threshold voltage) or the loss of functionality (inability to turn-off). The failure causes can be due to environmental conditions or operating conditions.   9. Is IGBT unipolar or bipolar? The IGBT cannot conduct current in the reverse direction (from emitter to collector) even with a positive Vge applied to it, because it has a bipolar-type structure.   10. Which IGBT used in VFD? IGBT (insulated gate bipolar transistor) provides a high switching speed necessary for PWM VFD operation. IGBTs are capable of switching on and off several thousand times a second. A VFD IGBT can turn on in less than 400 nanoseconds and off in approximately 500 nanoseconds.   11. Can we use IGBT instead of Mosfet? Due to the higher usable current density of IGBTs, it can usually handle two to three times more current than a typical MOSFET it replaces. This means that a single IGBT device can replace multiple MOSFETs in parallel operation or any of the super-large single power MOSFETs that are available today.   12. How fast can an IGBT switch? The typical switching time of IGBT is about hundreds of nanoseconds and the value varies with load current, junction temperature, and other factors [17–20]. However, the change of IGBT switching time is very small [4,5] (range from several to tens of nanoseconds) when the health status of the IGBT module changes.   13. Is IGBT faster than Mosfet? When compared to the IGBT, a power MOSFET has the advantages of higher commutation speed and greater efficiency during operation at low voltages. ... The IGBT combines the simple gate-drive characteristics found in the MOSFET with the high-current and low-saturation-voltage capability of a bipolar transistor.   14. How many IGBT are in a VFD? Six IGBTs. In a typical six pulse drive there are six IGBTs pulsing voltage up to 15,000 times per second. Since their introduction in the 1980's, IGBTs have literally switched up the market and now play a large role in many modern day power electronics applications where speed and process control are needed.   15. What is the function of IGBT? The IGBT combines, in a single device, a control input with a MOS structure and a bipolar power transistor that acts as an output switch. IGBTs are suitable for high-voltage, high-current applications. They are designed to drive high-power applications with a low-power input.   16. Is IGBT a rectifier? IGBTs have a pretty good current handling capacity when compared to standard BJTs (Bipolar junction transistor) and MOSFETs (metal–oxide–silicon transistor). IGBTs are devices whose switching is fully controlled electronically. Most standard rectifiers in the market are typically 6-pulse rectifiers.   17. How many types of IGBT are there? two types. The IGBT is classified as two types based on the n+ buffer layer, the IGBTs that are having the n+ buffer layer is called the Punch through IGBT (PT-IGBT), the IGBTs that does not have an n+ buffer layer are called the Non-Punch Through- IGBT (NPT- IGBT).   18. How do you prevent IGBT failure? IGBT turn-off requires that the IGBT be driven to the cutoff region of operation so that it can successfully block the reverse high voltage across it once the high-side IGBT has turned on. In principle this can be achieved by reducing the IGBT gate-emitter voltage to 0 V.   19. What is the difference between unipolar and bipolar devices? As their name implies, Bipolar Transistors are “Bipolar” devices because they operate with both types of charge carriers, Holes and Electrons. The Field Effect Transistor on the other hand is a “Unipolar” device that depends only on the conduction of electrons (N-channel) or holes (P-channel).   20. What is IGBT and Igct? GTO stands for Gate Turn-Off Thyristor, IGCT stands for Insulated Gate Commutated Thyristor and IGBT stands for Insulated Gate Bipolar Transistor. The comparison between the three devices are derived with respect to symbol, characteristic, advantages, disadvantages and applications.   You May Also Like The First Fully 2D FETs Lead A Faster Electronic Future The First Printed 2D Transistor Is Discovered by Researchers The First Chemical Circuit Developed Smarter transistors could be three times more efficient