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IntroductionFor people who have been in touch with digital circuits or analog circuits, the 555 IC is definitely classic work. With its low cost and reliable performance, it is widely used in various electrical appliances, including instruments and meters, household appliances, electric toys, and automatic control. The 555 timer only needs a few external resistors and capacitors to realize pulse generation and conversion circuits, such as multiple oscillators, monostable triggers and schmitt triggers. So how does it work in the circuit? What the role of its circuit? Here gives several typical 555 circuit examples for specific analysis.555 Timers Circuit LearningCatalogIntroductionⅠ Basic 555 Timer Circuit AnalysisⅡ 555 Multivibrator Circuit AnalysisⅢ 555 Timer Monostable Flip Flop Circuit AnalysisⅣ Classic 555 Timer Circuits DiagramsⅤ 555 Timer IC ModesⅠ Basic 555 Timer Circuit Analysis555 Means What?555 timer is a convenient and powerful IC, which is widely used in signal generation, conversion, control and detection. The origin of this name, because it is divided by three 5KΩ resistors. The 555 timer is a simple integrated circuit that can be used to make many different electronic circuits. With the following circuits analysis you will know how 555 IC works.Figure 1. Basic 555 Timer Circuit✔️ Circuit AnalysisR is not the reset terminal, when set to 0, Q is 0,  is 1, Uo outputs 0, and is 1 added to the base of the transistor T, the transistor is in the conducting state.① When R=0, Q=1, uo=0, T is saturated and turned on.② When R=1 (there is no reset function at this time):UTH>2VCC/3, UTR>VCC/3, C1=0, C2=1, Q=1 or =0, uo=0, T is saturated and turned on. (Analysis: C1's positive input terminal is 2VCC/3, C1's negative input UTH terminal is greater than the positive input terminal, working in saturation, and output 0. C2's negative input terminal is 1VCC/3, which is smaller than the positive input Terminal UTH, and outputs 1. There is a horizontal line above RD and SD, which means low level, meaning is Reset. C1 outputs 0, RD is valid, then Q is 0, not 1, Uo outputs 0, and is not acting on the base of the triode.)③ When R=1, UTH<2VCC/3, UTR>VCC/3, C1=1, C2=1, Q and remain unchanged, uo and T remain unchanged. (Analysis is the same as above)④ When R=1, UTH＜2VCC/3, UTR＜VCC/3, C1=1, C2=0, Q=0, =1, uo=1, T is cut off. (Analysis is the same as above) Learn how the inputs interact with the supply voltage to trigger and reset the output high and low. Find out which pins can be used to adjust the threshold at which that change happens.Ⅱ 555 Multivibrator Circuit AnalysisFigure 2. 555 Multivibrator Circuit Analysis Figure 3. 555 Multivibrator Circuit Example✔️ Circuit Analysis First, the power supply VCC charges the capacitor C through R1 and R2, and the voltage of the capacitor must be relatively small, less than 1VCC/3. Similarly, the positive terminal of C1 is 2VCC/3, the negative terminal of C2 is 1VCC/3, and the TH and TR terminals are connected At the same time, it is less than 1VCC/3 at the beginning. At this time, C1 outputs 1, C2 outputs 0, and the set terminal is valid (with detailed confirmation): Q is 1, is not 0, and uo is 1, the transistor is cut off, and outputs high level. At this time, the power supply is still charging the capacitor. When the TH and TR terminals are connected together, the voltage is less than 2VCC/3 and greater than 1VCC/3; C1 outputs 1, C2 outputs 1, the transistor is cut off, and uo is 1. When the capacitor is greater than 2VCC/3, C1 outputs 0 and C2 outputs 1. At this time, Q is 0, is not 1, uo is 0, the output is low, and the transistor is turned on. The capacitor will be discharged through pin 7. After this, the voltage at the point where TH and TR connected will gradually decrease, less than 2VCC/3 and greater than 1VCC/3, and then it will be less than 1VCC/3, to form a harmonic oscillator.The pulse width tp1 of the first transient state, that is, the time required for uc to rise from VCC/3 charging to 2VCC/3 (charged through two resistors):The second transient state pulse width tp2, that is, the time required for uc to discharge from 2VCC/3 to VCC/3:Duty cycle: the time that the high level occupies the entire cycle., it can be seen that its duty cycle is always greater than 50%.Examples 1Circuit with Adjustable Duty Cycle (add an adjustable resistor)Figure 4. Circuit with Adjustable Duty Cycle (add an adjustable resistor)It can be calculated:Where T1=0.7R1C (T1 is charging time), T2=0.7R2C (T2 is discharging time)Total time T=T1+T2=0.7(R1+R2)CSo R1, R2, and C are determined, and the period T is also determined.Duty Cycle Calculation Example 2Circuit with Adjustable Duty Cycle (1KHz)Figure 5. Circuit with Adjustable Duty Cycle (1KHz)✔️ Circuit AnalysisT = 0.7(R1+R2)C, f = 1/T, the duty cycle circuit only needs to adjust the resistance value. Ⅲ 555 Timer Monostable Flip Flop Circuit AnalysisWorking Characteristics① It has two different working states: steady state and transient state.② Under the action of an external trigger pulse, it can switch from the steady state to the transient state. After the transient state is maintained for a period of time, the circuit can automatically return to the steady state.③ The transient state cannot be maintained for a long time, and the duration of its sustaining time depends on the parameters of the circuit itself and has nothing to do with the trigger pulse. So what is the principle of a monostable circuit?Figure 6. 555 Timer Monostable Circuit Analysis Figure 7. 555 Timer Monostable Circuit Example✔️ Circuit AnalysisFirst, the TR terminal is at a high level ui, which must be greater than 1VCC/3. At this time, C2 outputs 1, and the power supply charges capacitor C through R. The charging voltage is less than 1VCC/3 (TH), CO voltage is equal to 2VCC/3, C1 outputs 1, and it is in the holding state at this time. Assuming that the non-reset terminal of R is reset before power on, the output of uo is 0, and then the previous state is still maintained and the output is 0 at this time. is 1, the transistor is turned on, the capacitor is discharged through pin 7, and uc is zero level. At a certain moment, ui is low, C1 still outputs 1, C2 outputs 0, Q is 1, is 0, uo outputs 1 (high level), and the transistor has been in the cut-off state. At this time, VCC can charge the capacitor (uc is getting larger). When uc is between 1VCC/3~2VCC/3, assuming that the TR terminal returns to the original state (high level), C1 outputs 1 , C2 outputs 1, at this time uo keeps in original state, it is still 1, and the transistor is in the cut-off state. When uc is greater than 2VCC/3, C2 is still 1, C1 output is 0, Q is 0, is 1, and uo is 0, the transistor is turned on and in a discharging state, at this time, uc is getting smaller and smaller.Summery:1. As long as a low-level trigger signal is given, the temporary stable stay time is the charging time of voltage 0V~ 2Ucc/3 (the time represented by tp).2. Charging time Tp=1.1RC3. It can be used as a timing circuit, and the time can be determined by RC.Example: Timing Circuit Design (1s delay time)Figure 8. 555 Timer Delay Circuit ExampleⅣ Classic 555 Timer Circuits DiagramsThere are A LOT of projects out there using the 555 in various ways and it’s easy to find schematics to make a project that has already been proven. Here lists some typical projects using 555 timer in circuits. Let’s have a look. 🔺 Car Tachometer🔺 SIREN🔺 Flashing Lights🔺 Knight Rider Circuit🔺 Laser Ray🔺 Latch🔺 LED Dimmer🔺 555 Amplifier🔺 Light Detector🔺 Machine Gun🔺 Metal Detector🔺 Motor PWM🔺 Music Box🔺 Zener Diode Tester Ⅴ 555 Timer IC Modes555 timer will use different models in different circuits to meet circuit requirements. Therefore, it has many derivative models produced by different companies with different pin functions, and uses CMOS design. What;s more, some chips include several integrated 555 timers. Some common models of the 555 chip family are as follows:ManufacturerModelRemarksCustom Silicon SolutionsCSS555/CSS555CCMOS chip, minimum working voltage 1.2V, IDD < 5µACEMIULY7855*ECG SemiconductorsECG955MTimer Single Rc-type OscillatorExarXR-555Highly stable controllerFairchildNE555/KA555Time-delay or mono-stableHarrisHA555*IK SemiconILC555CMOS chip, minimum working voltage 2VTexas InstrumentsSE555/NE555*RenesasICM7555CMOS RC timersLithic SystemsLC555Available in Industry's Smallest 8-Bump DSBGAMaximICM7555CMOS RC timers, minimum working voltage 2VMotorolaMC1455/MC1555Monolithic timerNational SemiconductorLM1455/LM555/LM555C*National SemiconductorLMC555CMOS chip, minimum working voltage 1.5VNTE SylvaniaNTE955MAccurate time delaysRaytheonRM555/RC555*RCACA555/CA555C*STMicroelectronicsNE555N/ K3T647*Texas InstrumentsSN52555/SN72555*Texas InstrumentsTLC555CMOS chip, minimum working voltage 2VZetexZSCT1555Precision single cell timerNXPICM7555CMOSHitachi SemiconductorHA17555Accurate time delays or oscillations Frequently Asked Questions about 555 Timer Circuit1. What does a 555 timer do in a circuit?The 555 timer IC is a very cheap, popular and useful precision timing device which can act as either a simple timer to generate single pulses or long time delays, or as a relaxation oscillator producing a string of stabilised waveforms of varying duty cycles from 50 to 100%. 2. How much voltage can a 555 timer take?The standard TTL 555 can operate from a supply voltage between 4.5 volts and 18 volts, with its output voltage approximately 2 volts lower than its supply voltage VCC. The 555 can source or sink a maximum output current of 200mA, (but it may get hot at this level), so the circuit variations are unlimited. 3. What are the modes of operation of a timer?The timer registers can be used in two modes. These modes areTimer mode and the Counter mode. The only difference between these two modes is the source for incrementing the timer registers. 4. What are the basic operation modes of the 555 timer?The operating modes of a 555 timer are astable, bistable and monostable. Each mode of operation signifies with a circuit diagram and its output. 5. What is the maximum frequency of a 555 timer?2MHzaccording to the website, the 555 timer has a maximum frequency of 2MHz.

This article is an introduction article on the resonator, information like its working principle, types, and some main parameters will be introduced in detail, also including the analysis of the difference between resonator and oscillator.     Catalog I. What is A Resonator? II. The Working Principle of Resonator      2.1 The Structure of Resonator      2.2 Piezoelectric Effect III. Resonator Types IV. Main Parameters of Resonator V. What’s the Difference Between Resonator and Oscillator? 5.1 General Difference Between Resonator &   Oscillator 5.2 Pros and Cons Analysis of Resonator &   Oscillator FAQ   I. What is A Resonator? This video introduce resonator in details.   A resonator refers to an electronic component that generates a resonant frequency.   A resonator refers to an electronic component that generates a resonant frequency. It is a typical passive device and requires a peripheral circuit to drive its work to generate a clock output.   Crystal resonators are commonly divided into quartz crystal resonators and ceramic resonators. The function of generating frequency has the characteristics of stability and good anti-interference performance and is widely used in various electronic products.   The frequency accuracy of quartz crystal resonators is higher than that of ceramic resonators, but the cost is also higher than that of ceramic resonators. The resonator mainly plays the role of frequency control, and all electronic products involve frequency transmission and reception require a resonator. The types of resonators can be divided into the in-line type and patch type according to their appearance. II. The Working Principle of Resonator   2.1 The Structure of Resonator   Quartz crystal resonator is a kind of resonant device made by using the piezoelectric effect of quartz crystal (a crystal of silicon dioxide).   Its basic composition can be roughly described as follows: cut a thin slice (referred to as a wafer, which can be square, rectangular or circular, etc.) from a piece of quartz crystal at a certain azimuth angle, and coat silver layers as electrodes on its two corresponding surfaces. Weld a lead wire on each electrode to the pin, and add a package shell to form a quartz crystal resonator. Its products are generally packaged in metal shells, but also in glass, ceramic or plastic packages.   2.2 Piezoelectric Effect   If an electric field is applied to the two electrodes of the quartz crystal, the wafer will be mechanically deformed. Conversely, if mechanical pressure is applied to both sides of the wafer, an electric field will be generated in the corresponding direction of the wafer. This physical phenomenon is called the piezoelectric effect.   If an alternating voltage is applied to the two poles of the wafer, the wafer will produce mechanical vibration, and at the same time, the mechanical vibration of the wafer will produce an alternating electric field. In general, the amplitude of the mechanical vibration of the wafer and the amplitude of the alternating electric field is very small, but when the frequency of the applied alternating voltage is a certain value, the amplitude is obviously increased, which is much larger than the amplitude at other frequencies. This phenomenon is called piezoelectric resonance, which is very similar to the resonance phenomenon of the LC circuit. Its resonant frequency is related to the cutting method, geometry, and size of the wafer. III. Resonator Types   Quartz crystal resonators are composed of quartz crystal resonators (ie resonators and oscillation circuits) with extremely high-quality factors. The quality of the crystal, the cutting orientation, the structure of the crystal oscillator and the circuit form, etc., jointly determine the performance of the resonator.   The International Electrotechnical Commission (IEC) divides quartz crystal resonators into 4 categories: ordinary crystal oscillator (SPXO), voltage-controlled crystal resonator (VCXO), temperature compensated crystal oscillator (TCXO), and thermostatically controlled crystal oscillator (OCXO). Digitally compensated crystal loss oscillation (DCXO) is currently under development.   (1) Ordinary crystal resonator (SPXO) can produce frequency accuracy of the order of 10-5～10-4, the standard frequency is 100MHZ, and the frequency stability is ±100ppm. SPXO does not use any temperature and frequency compensation measures are low in price and are usually used as a clock device for microprocessors. The package size ranges from 21×14×6mm and 5×3.2×1.5mm.   (2) The accuracy of the voltage-controlled crystal resonator (VCXO) is in the order of 10-6 to 10-5, and the frequency range is 1 to 30 MHz. The frequency stability of the low-tolerance resonator is ±50ppm. Usually used in phase-locked loops. The package size is 14×10×3mm.   (3) The temperature-compensated crystal resonator (TCXO) uses temperature-sensitive devices for temperature and frequency compensation, with a frequency accuracy of 10-7～10-6, a frequency range of 1-60MHz, and frequency stability of ±1～±2.5ppm, The package size ranges from 30×30×15mm to 11.4×9.6×3.9mm. Usually used in handheld phones, cellular phones, two-way wireless communication devices, etc.   (4) The thermostatically controlled crystal resonator (OCXO) places the crystal and oscillation circuit in a thermostat to eliminate the influence of environmental temperature changes on the frequency. The frequency accuracy of OCXO is in the order of 10-7～10-8, even higher for some special applications. The frequency stability is the highest among the four types of resonators. IV. Main Parameters of Resonator   The main parameters of the crystal oscillator are nominal frequency, load capacitance, frequency accuracy, frequency stability, etc. Different crystal oscillators have different nominal frequencies, and most of the nominal frequencies are marked on the crystal housing.   For example, the nominal frequencies of common ordinary crystal oscillators are 48kHz, 500 kHz, 503.5 kHz, 1MHz～40.50 MHz, etc. The frequency of crystal oscillators with special requirements can reach 1000 MHz or more, and there are also non-nominal frequencies, such as CRB, ZTB, Ja, etc.   The load capacitance refers to the sum of all the effective capacitances inside and outside the IC block connected by the two leads of the crystal oscillator, which can be regarded as the series connection capacitance of the crystal oscillator in the circuit. The different load frequency determines the different oscillation frequency of the resonator. For crystal oscillators with the same nominal frequency, the load capacitance may not be the same.   Because the quartz crystal resonator has two resonant frequencies, one is a low-load capacitance crystal of a series resonant crystal oscillator, and the other is a high-load capacitance crystal of a parallel resonant crystal. Therefore, when the crystal oscillators with the same nominal frequency are exchanged, the load capacitance must be the same, and they cannot be exchanged rashly, otherwise, it will cause the electrical appliances to work abnormally.   Frequency accuracy and frequency stability: Because the basic performance of ordinary crystal oscillators meets the requirements of general electrical appliances, certain frequency accuracy, and frequency stability are required for high-end equipment. Frequency accuracy varies from magnitude to magnitude. The stability varies from ±1 to ±100ppm. Choosing the appropriate crystal oscillator according to the specific equipment needs, such as communication network, wireless data transmission and other systems require a more demanding quartz crystal resonator.   Therefore, the parameters of the crystal oscillator determine the quality and performance of the crystal oscillator. In practical applications, the appropriate crystal oscillator should be selected according to specific requirements. Because of the different prices of crystal oscillators with different performances, the higher the requirements, the more expensive the price. Generally, the choice only needs to meet the requirements. V. What’s the Difference Between Resonator and Oscillator?     5.1 General Difference Between Resonator & Oscillator   The so-called resonator includes not only quartz crystal resonators but also ceramic resonators, LC resonators, and so on. A crystal oscillator is the abbreviation of the crystal oscillator. It is an oscillator component composed of a combination of a crystal resonator and a circuit, especially an oscillator component made of a quartz crystal.   So the complete naming should be "Quartz Crystal Resonator" and "Quartz Crystal Oscillator". In addition, the resonator is a passive device, which requires a peripheral circuit to drive its work and generate a clock output. The oscillator is an active device with its own built-in circuit to provide a more stable clock output.   A crystal oscillator is an oscillating circuit that uses a crystal as a frequency-selecting component. Compared with other oscillating circuits, it has the advantages of good frequency selection characteristics (high Q value) and high-frequency stability.   The fundamental difference between a resonator and an oscillator is active and passive, which can also be said to be active and passive. The oscillator has one more control circuit than the resonator.   Crystal resonators have some equivalent parameters, and different use environments may have different requirements. For example, some users require load capacitance C0 / C1. When selecting, consider the environmental temperature, load capacitance, frequency accuracy, and even DLD requirements. This requires some control of the parameters of the peripheral oscillator circuit to output a stable frequency.   The crystal oscillator avoids these troubles. The oscillating circuit has been completed by the manufacturer, and only a stable power supply is needed to have a stable output. In addition, the oscillator has some auxiliary functions, such as voltage-controlled crystal oscillator (VCXO), temperature-compensated crystal oscillator (TCXO), constant temperature crystal oscillator (OCXO), etc. These oscillators can meet some precision controls that are difficult to achieve when directly using resonators. . The frequency accuracy of OCXO can reach the order of E-9.   Secondly, the crystal oscillator is made of a crystal resonator, in order to be used as a signal carrier or timing on other components. To meet the requirements of the products produced.   An oscillator is simply a frequency source and is generally used in a phase-locked loop. In detail, it is a device that can convert DC power into AC power without external signal excitation. Generally divided into two types: positive feedback and negative resistance.   The so-called "oscillation", its meaning implies exchange, the oscillator includes a process and function from no oscillation to oscillation. It can complete the conversion from DC power to AC power. Such a device can be called an "oscillator."   Any communication or electronic system should have a level value within a normal range at some given point. The components that are adjusted to the normal level value are amplifiers and attenuators. The point of excessively low level is the point where noise is introduced, and the point of excessively high level will cause overload and make the amplifying component appear intolerable nonlinear distortion. It is not difficult to understand the role of the attenuator. There are two types of attenuators: fixed and variable.     5.2 Pros and Cons Analysis of Resonator & Oscillator   In this sector, we are going to analyze the pros and cons of crystal resonator and ceramic resonator, resonator, and oscillator.   (1) pros and cons of crystal resonator and ceramic resonator   The introduction of the crystal resonator has been mentioned above, so I won't repeat it here. Let's take a look at ceramic resonators.   A ceramic resonator is a piezoelectric ceramic device used to oscillate at a specific frequency. The materials used to make such devices excite resonance characteristics during the production process.   Because this resonance characteristic is within the production error range, and its quality factor is much lower than that of quartz, the frequency stability that ceramic resonators can provide is not as good as crystal resonators. Generally, ceramic resonators are used in occasions where the cost is low and the performance requirements are not high.   Pros: Compared with crystals, the cost of ceramic resonators is only half that of crystals and the size is smaller.   Cons: Compared with crystals, it lacks frequency and temperature stability. Its accuracy is poor, probably between 1% and 0.1%.     (2) pros and cons of resonator and oscillator   The oscillator is an energy conversion device that converts DC power into AC power with a certain frequency. The circuit formed by it is called an oscillator circuit. The oscillator is an active device. The oscillator has one more control circuit than the resonator.   Oscillators are electronic components used to generate repetitive electronic signals (usually sine waves or square waves). The circuit formed by it is called an oscillating circuit. An electronic circuit or device that can convert direct current into an alternating current signal with a certain frequency.   There are many types. According to the oscillation excitation mode, it can be divided into the self-excited oscillator and separately excited oscillator; according to the circuit structure, it can be divided into the resistance-capacitance oscillator, inductance-capacitance oscillator, crystal oscillator, tuning fork oscillator, etc.; according to the output waveform can be divided into It is a sine wave, square wave, sawtooth wave, and other oscillators. It is widely used in the electronics industry, medical treatment, scientific research, etc.   Pros: The crystal oscillator signal quality is good, relatively stable, and the connection method is relatively simple (mainly to do a good job of power filtering, usually a PI filter network composed of a capacitor and an inductance is used, and the output terminal uses a small resistance resistor to filter the signal. Yes), no complicated configuration circuit is required. For applications with sensitive timing requirements, the performance of crystal oscillators is relatively good.   Cons: Compared with the crystal resonator, the defect of the crystal oscillator is that its signal level is fixed, and the appropriate output level needs to be selected. It is less flexible and expensive. In addition, the quartz oscillator takes a long time to start.   Volume: Compared with passive crystals, crystal oscillators are usually larger in volume. With the improvement of technology, some crystal oscillators are now surface-mounted, and the volume is comparable to crystal resonators.   Summary: The typical initial accuracy of ceramic resonators is in the range of 0.5% to 0.1%, and drift caused by aging or temperature changes may change this accuracy range.   The tolerances of cheap ceramic resonators are only ±1.1%, and the accuracy of higher-end automobiles is ±0.25% and ±0.3%, respectively. The future application lies in the automotive CAN (controller area network) bus application with an operating temperature of -40°C to +125°C. Low-cost ceramic resonators with frequencies ranging from 200 kHz to about 1 GHz are suitable for embedded systems that do not have strict timing requirements.   Ceramic devices start faster and are generally smaller than quartz devices. They are also more able to withstand shock and vibration.     FAQ   1. What does a resonator do? A resonators' sole purpose in life is to change a vehicle's engine noise before it reaches the muffler for a final decibel reduction.   2. What is a resonator in electronics? A resonator is a device or system that exhibits resonance or resonant behavior. ... Resonators are used to either generate waves of specific frequencies or to select specific frequencies from a signal. Musical instruments use acoustic resonators that produce sound waves of specific tones.   3. What does removing the resonator do? A resonator delete changes the way that the pulses generated by your vehicle move through the exhaust system. Think of this device as if it were a large echo chamber. It takes those pulses, optimizes their frequencies, and this makes it possible to achieve better power production.   4. Which is better muffler delete or resonator delete? If you want a louder and lighter vehicle, you'll be better off with the muffler delete. If you're after a good sound and a little more power, the resonator delete is the way to go. ... After all, the difference between a resonator delete and muffler delete isn't that significant.   5. What is difference between crystal and resonator? The ceramic resonator utilizes a frequency within the electrical component but unlike the crystal which has a frequency tolerance of 10~30 PPM , a ceramic resonator carries a 0.5% or 5,000 PPM frequency tolerance which is generally used in microprocessor applications where absolute stability is not important.   6. Is intake resonator necessary? An air intake resonator is a crucial component to an automobile engine's intake system. It allows the engine to run more quietly as well as more efficiently. ... An air intake resonator is a crucial component to an automobile engine's intake system. It allows the engine to run more quietly as well as more efficiently.   7. Do resonators restrict airflow? Magnaflow resonators dont restrict flow at all, its just like adding a section of straight pipe as they are straight through. magnaflow's design uses no chambers, but rather a perforated straight pipe surrounded by a sound-absorbing material.   8. Which is the best frequency for a noise resonator? The resonator is designed to work best in the frequency range where the engine makes the most noise; but even if the frequency is not exactly what the resonator was tuned for, it will still produce some destructive interference.   9. Will a resonator quiet my exhaust? Mufflers and resonators work together to quiet your car's exhaust and reduce annoying sounds. While they function differently, they both help improve your exhaust note. Mufflers and resonators can also be deleted for a louder, more aggressive exhaust sound.   10. Does removing the resonator increase horsepower? As a rule; the quieter an exhaust system is, the more horsepower it is stealing from your engine. ... Removal of all mufflers and resonators will provide slightly greater increases but remember as the restrictions are removed the exhaust grows louder.  

IntroductionAs everyone knows, in order to create a passive low pass filter, combing resistive elements with reactive elements happens often. Put simply, a typical circuit composed of resistors and capacitors or inductors. According to theories, the resistor–inductor (RL) low-pass topology is equivalent to the resistor-capacitor (RC) low-pass topology in terms of filtering capability. However. in fact, RC low pass filters are more common, so this article will focus on first-order RC low pass filters.In this video, Passive RC Low Pass Filter has been discussed. CatalogIntroductionⅠ Typical RC Circuit1.1 Time Domain1.2 Frequency DomainⅡ First-order Low Pass Filter on Software2.1 Basic Filtering Algorithm2.2 Basic Algorithm of First-order RC Digital FilteringⅢ Optimization Method- Filtering Coefficients AdjustmentⅠ Typical RC CircuitThe RC circuit has thousands of uses and is a very important circuit to study. Not only can it be used to time circuits, it can also be used to filter out unwanted frequencies in a circuit and used in power supplies, like the one for your computer, to help turn ac voltage to dc voltage.Figure 1. Typical RC Circuit (DC, AC, and Pulse Signals can all use it)1.1 Time DomainCapacitor Current:According to Kirchhoff’s Voltage Law:Where, the unit of Ui is volts, the unit of RC is seconds, and τ=RC, get:Suppose the initial voltage of the capacitor is 0, where:R=1000ΩC=4.7uFUi=1Vt=0.0001~0.1sτ=RCVc(τ)=0.632 Figure 2. Step Response Curve of a First-order RC System1.2 Frequency DomainTaking the capacitor voltage as the output, the network function of the circuit is:Where u1=Ui, u2=UoLet ωc be equal to:, which is the cut-off frequency.Amplitude and phase angle function:Value of variables:R=1000ΩC=4.7uF |A(fc)|=0.707θ(fc)=-45, f=0.001, 1, …….100000.Amplitude and phase frequency characteristics:Figure 3.Figure 4.Logarithmic representation of amplitude-frequency characteristic:Figure 5.Analysis:When ω<ωc, the amplitude is a straight line parallel to the coordinate, and there is no attenuation.　When ω>ωc, it is a straight line whose slope is proportional to -20dB/decade.When ω=ωc, the gain is attenuated to 0.707, which is -3dB, and the phase lags by 45 degrees, corresponding to a low-pass filter. This frequency is usually called the cutoff frequency. Disadvantages:When using this analog filter to suppress low-frequency interference, the filter is required to have a larger time constant and a high-precision RC network. Increasing the time constant requires increasing the value of R, and meanwhile, the leakage current increases accordingly, thereby reducing the filtering effect.Figure 6. RC CircuitⅡ First-order Low Pass Filter on SoftwareAdvantages1) The use of digital filtering algorithms to achieve dynamic RC filtering can well overcome the shortcomings of analog filters.2) This kind of algorithm is more practical when the simulation constant is required.3) It has a good inhibitory effect on periodic interference.4) Save RAM space Disadvantages1) Exit phase lag, resulting in low sensitivity.2) It cannot filter out interference with a frequency higher than half of the sampling frequency (called the Nyquist frequency. For example, if the sampling frequency is 100 Hz, it cannot filter out interference signals above 50Hz). In this case, an analog filter should be used.3) For the single-chip microcomputer without multiplication and division running instructions, the workload of the program operation is relatively large.2.1 Basic Filtering AlgorithmOrigin of the AlgorithmThe transfer function of the first-order RC low-pass filter in the S domain for frequency analysis:Through z-transformation (there are many methods, such as first-order forward difference, bilinear transformation, etc. Here, the first-order backward difference method is used): Into the S-domain Transfer Function After the derivation is transformed into the difference equation, we can get:The transfer function in the S domain can be transformed into a difference equation in the time domain through the Z transformation.2.2 Basic Algorithm of First-order RC Digital FilteringX is the input, Y is the output value after filtering, then: a is a parameter related to the RC value, called the filter coefficient, its value determines the weight of the new sample value in the filtering result of this time, and its value is usually far less than 1, when the sampling interval t is small enough:1) The smaller the filtering coefficient, the smoother the filtering result, but the lower the sensitivity.2) The larger the filtering coefficient, the higher the sensitivity, but the more unstable the filtering result.3) The output value this time mainly depends on the last filtered output value, and the current sampled value has a relatively small effect on this output, which plays a corrective role.4) Cutoff frequencyFor example: t=0.5s (f=2Hz), a=1/32where fl=(1/32)/(2*3.14*0.5)=0.01Hz Basic ProgramWrite the program according to the basic principles and formulas of first-order filter, as follows:/*In the program, integer arithmetic is faster than decimal arithmetic. In order to speed up the processing speed of the program, for calculation convenience, a is an integer (from 0~255), 1-a is replaced by 256-a, which means that the new sample value is being filtered. The weight in the result (you can also change the base of 1-a to 100-a, and the calculation result will be processed accordingly)*/#define a 128 char value; //Last filtering valuechar filter(){    char new_value;    new_value=get_ad();//Sampling value    return(256-a)*value/256+a*new_value/256；}Initial Optimization of the ProgramReduce the number of operations of multiplication and division to increase the speed of operations.Specific optimization methods:First compare the new sampled value with the previous filtering result, and then use different formula calculations based on the comparison, so that the calculation efficiency of the program is doubled.Resolve the basic formula to get: ProcessNotes:S → New Sampling ValueR → Previous Filtering ResultC→ Filter CoefficientN→ New Filtering Result Program/*Int: NEW_DATA     New sampling values       OLD_DATA       Last filtering result       k        Filter coefficient (0~255)  Out:         The filtering results */ char filter_1(char NEW_DATA,char OLD_DATA,char k){    int result;    if(NEW_DATA<OLD_DATA)    {        result=OLD_DATA-NEW_DATA;        result=result*k;        result=result+128;//+128 Round Up        result=result/256;        result=OLD_DATA-result;    }    else if(NEW_DATA>OLD_DATA)    {        result=NEW_DATA-OLD_DATA;        result=result*k;        result=result+128;//+128 Round Up        result=result/256;        result=OLD_DATA-result;    }    else result=OLD_DATA;    return((char)result);} Filtering AnalysisWhen the filtering coefficient is 30:Figure 7.When the filtering coefficient is 128:Figure 8.When the filtering coefficient is 200:Figure 9.It can be seen that the smaller the filtering coefficient, the smoother the filtering result, but the lower the sensitivity. On the contrary, the larger the filtering coefficient, the higher the sensitivity, but the more unstable the filtering result.Insufficient1) The contradiction between sensitivity and smoothness2) Errors caused by discarding decimals.For example: the current sampling value=25, the last filtering result=24, and the filtering coefficient=10;According to the algorithm, the filtering result of this time = 24.0390625In single-chip microcomputers, floating-point numbers are rarely used, and the fractional part is either discarded or needs to round up. In this way, the result is 24. If the sampling value is always 25, the result will always be 24. Because the filtering result and the actual data will always have an error that cannot be eliminated. Sometimes it will cause the filtering result curve to deviate from the actual value when the sampling data is stable at a certain value (that is, there is a large error between the filtering result and the actual result although in a stable case). Be Careful1) Changing the filtering coefficient, increasing it will reduce the smoothness, and if it is too large, the filtering will lose its meaning.2) The use of decimal part in calculations will bring heavy computational pressure to the CPU. Ⅲ Optimization Method- Filtering Coefficients AdjustmentRealize the Function1) When the data changes rapidly, the filtering results can be followed up in time, and the faster the data changes, the higher the sensitivity should be (sensitivity priority principle).2) When the data becomes stable and oscillates within a range, the filtering result can become stable (the principle of stability first).3) When the data is stable, the filtering result can be approximated and finally equal to the sampling data (eliminate the error caused by decimals in the calculation). Judgment before Adjustment1) Whether the data changes consistently. For example, when the two consecutive sampling values are larger than the previous filtering result, it is normal, otherwise it is regarded as inconsistent.2) Whether the data changes quickly, which is to judge the difference between the sampling value and the previous filtering result.Adjustment Principle1) When the two data changes are inconsistent, it means there is jitter. Clear the filtering coefficient to zero, and delete the new sampling value.2) When the data changes consistently, gradually increase the filtering coefficient to provide the weight of this sampling.3) When the data changes quickly (difference value> debounce count acceleration response threshold), the filtering coefficient should be increased quickly. Adjusting Filter Coefficient Process① Calculate the difference (absolute value) between the current sampling value and the last filtering result; Set the data change direction flag.② Two changes in the same direction?③ First order filter coefficient + coefficient increment (the maximum value is taken when the result is greater than the maximum value). Several Constant Parameters and Their Ranges1. Debounce counting acceleration response threshold is determined according to the actual situation.2. The maximum value of debounce count, which is generally 10.3. The increment of filtering coefficient range is 10~30.4. The maximum value of the filtering coefficient is generally 255.Before starting the first-order filtering program, open the adjustment filter coefficient program to adjust the coefficients in real time. Filtering Effect1. When the sampled data is accidentally interfered, the interference in the filtering result is completely filtered out.2. When the data oscillates within a range, the filtering result curve is very smooth, almost a straight line.3. When the sampling data has real changes, the filtering results can be followed up in a relatively timely manner.4. When the sampling data becomes stable, the filtering result gradually approaches and is finally equal to it.Finally, improve the algorithm. Taking into account the requirements of sensitivity and stability; and meanwhile, it does not consume too much RAM space. As long as a few constants are adjusted reasonably, the algorithm is more suitable for practical applications. Frequently Asked Questions about RC Low Pass Filter1. What is RC low pass filter?A low pass filter is a filter which passes low-frequency signals and blocks, or impedes, high-frequency signals. ... Low pass filters can be constructed using resistors with either capacitors or inductors. A low pass filter composed of a resistor and a capacitor is called a low pass RC filter. 2. Why RC circuit is low pass filter?Then by carefully selecting the correct resistor-capacitor combination, we can create a RC circuit that allows a range of frequencies below a certain value to pass through the circuit unaffected while any frequencies applied to the circuit above this cut-off point to be attenuated, creating what is commonly called a rc low pass fiter. 3. What is difference between RC low pass filter and RC high pass filter?Low pass filter is the type of frequency domain filter that is used for smoothing the image. It attenuates the high frequency components and preserves the low frequency components. High pass filter: ... It attenuates the low frequency components and preserves the high frequency components. 4. What is the transfer function of a low pass filter?Low Pass Filters and their Transfer FunctionsAs its name implies, a low pass filter is an electronic device that allows low frequency AC signals to pass a current through the filter circuit. The output from the filter circuit will be attenuated, depending on the frequency of the input signal. 5. How is low pass filter frequency calculated?The cut-off frequency or -3dB point, can be found using the standard formula, ƒc = 1/(2πRC). The phase angle of the output signal at ƒc and is -45o for a Low Pass Filter.

CatalogⅠ What is a Tantalum CapacitorⅡ Construction and Properties of Tantalum CapacitorⅢ Characteristics of Tantalum Capacitor  3.1 General Characteristic  3.2 Polarity  3.3 Failure Mode of Tantalum CapacitorⅣ Tantalum Capacitor Classification  4.1 Leaded Tantalum Capacitors  4.2 SMD Tantalum CapacitorsⅤ Applications for Tantalum CapacitorⅥ Difference Between Tantalum and Ceramic CapacitorⅦ FAQ Ⅰ What is a Tantalum CapacitorTantalum capacitors have a tantalum anode and are electrolytic capacitors. They're polarized capacitors that have excellent frequency and stability. Electrolytic capacitors with tantalum as a component are known as tantalum capacitors. They're made of tantalum metal, which serves as an anode, with a layer of oxide acting as a dielectric and a conductive cathode surrounding it.Tantalum is used to create a very thin dielectric layer. As a result, the capacitance value per volume is higher, the frequency characteristics are superior to many other types of capacitors, and the capacitor has excellent long-term stability. Tantalum capacitors are usually polarized, which means they can only be connected to a DC supply if the terminal polarity is maintained. The disadvantage of using tantalum capacitors is that they have an unfavorable failure mode, which can result in thermal runaways, fires, and minor explosions. This can be avoided by using external failsafe devices such as current limiters or thermal fuses. Tantalum capacitors can now be used in a wide range of circuits, including computers, automobiles, cell phones, and other electronic devices, most commonly surface-mounted devices (SMD). These surface-mount tantalum capacitors take up significantly less space on the printed circuit board, allowing for higher packing densities. It's worth noting that, like resistors, there are both fixed and variable capacitors. Capacitors with fixed values are classified as either non-polarized or polarized capacitors, depending on their polarity. The three most common capacitor types are represented by electric symbols in the figure below.Tantalum capacitor-capacitor symbols Ⅱ Construction and Properties of Tantalum CapacitorTantalum (Ta) is a silver-gray metal with the atomic number 73. When looking at a cross-sectional view of a tantalum capacitor, such as a standard SMD tantalum electrolytic chip capacitor with solid electrolyte shown in the Figure below, the positive (anode) terminal is tantalum powder pressed and sintered into a pallet. The dielectric is formed by an insulating oxide layer covering the positive (anode) terminal, and the negative (cathode) terminal is formed by a solid manganese dioxide electrolyte. Tantalum capacitor-construction of tantalum capacitor In the case of solid tantalum capacitors, the electrolyte is added to the anode through pyrolysis. To create a manganese dioxide coat, solid tantalum capacitors are dipped in a special solution and baked in an oven. The procedure is repeated until the pellet has a dense coating on both internal and external surfaces. Finally, to ensure a strong cathode connection, the pellet used in solid tantalum capacitors is dipped in graphite and silver. Wet tantalum capacitors, unlike solid tantalum capacitors, use a liquid electrolyte. The anode is dipped into a liquid electrolyte inside an enclosure after it has been sintered and a dielectric layer has been grown. In wet tantalum capacitors, the enclosure and electrolyte serve as the cathode. Tantalum capacitors have a high capacitance per volume and weight due to their thin, high permittivity dielectric sheet, which sets them apart from other electrolytic capacitors. Tantalum electrolytic capacitors are also ideal for passing or bypassing low-frequency signals and storing significant quantities of electric energy due to their large capacitance. Ⅲ Characteristics of Tantalum Capacitor3.1 General CharacteristicTantalum capacitors have capacitance values ranging from 1nF to 72mF and are significantly smaller than aluminum electrolytic capacitors of the same capacitance. Tantalum capacitors have voltage ratings ranging from 2V to more than 500V. They have a ten-fold lower equivalent series resistance (ESR) than aluminum electrolytic capacitors, allowing for higher currents to pass through the capacitor while generating less heat. As compared to aluminum electrolytic capacitors, tantalum capacitors are very stable over time and their capacitance does not change significantly with age. When handled properly, they are extremely dependable, and their shelf life is nearly limitless.3.2 PolarityTantalum electrolytic capacitors have a very high polarization. Although polarized aluminum electrolytic capacitors can survive a brief reverse voltage, tantalum capacitors are extremely sensitive to reverse polarization. When a voltage of the opposite polarity is applied, the dielectric oxide breaks down, resulting in a short circuit. This short circuit could lead to thermal runaway and the capacitor's destruction in the future. In comparison to aluminum electrolytic capacitors, which have their negative terminal marked on the casing, tantalum capacitors typically have their positive terminal marked.3.3 Failure Mode of Tantalum CapacitorAccording to a paper published by ASM International, the Tantalum capacitor failure mode is divided into three major groups. • High Leakage/ShortHigh leakage currents may result from applying reverse voltage, which is common during troubleshooting, malfunctions, and/or bench testing. Since the hotspots formed during crystallization heat the cathode, tantalum capacitors with crystallization cause short circuit failure.　　• High Equivalent Series Resistance (ESR)When a capacitor is exposed to board mounting, pick-and-place, reflow, and operation lifetime, the mechanical/thermomechanical has a significant impact on its ESR. External and/or internal relations are often harmed as a result of this form of stress, resulting in a high ESR. • Low Capacitance/OpenThe failure is uncommon since the capacitance of a Tantalum capacitor does not shift under normal operating conditions. A Tantalum capacitor's lower capacitance in any application may indicate a shorted capacitor, while an open failure can be caused by a damaged positive lead and wire link. Tantalum capacitors, as we all know, have a potentially dangerous failure mode. The tantalum anode may come into contact with the manganese dioxide cathode during voltage spikes, and if the energy of the spike is adequate, a chemical reaction may start. This chemical reaction generates heat and is self-sustaining, as well as the possibility of smoke and flame. External failsafe circuitry, such as current limiters and thermal fuses, should be used in combination with tantalum capacitors to avoid thermal runaway.  Ⅳ Tantalum Capacitor Classification4.1 Leaded Tantalum CapacitorsTo avoid damage, leaded tantalum capacitors are usually packaged in a small epoxy box. Tantalum bead capacitors are the name given to them because of their shape. Although a color-coding scheme was common at one time and some capacitors still use it, the capacitor markings are usually written directly onto the encapsulation as figures.Leaded tantalum capacitors 4.2 SMD Tantalum CapacitorsTantalum capacitors with a surface mount are commonly used in modern electronics. When designed with enough margins, they provide dependable service and allow for high capacitance values to be achieved in the small package sizes needed for modern equipment. Due to their inability to withstand the temperatures needed for soldering, aluminum electrolytes were not initially available in surface-mount packages. As a result, tantalum capacitors that could withstand the soldering process were nearly the only choice for high-value capacitors in surface-mount assemblies. Despite the availability of SMD electrolytic, tantalum remains the capacitor of choice for SMD due to its excellent cost, size, and performance parameters.SMD tantalum capacitor • SMD Tantalum Capacitor MarkingsSMD tantalum capacitors usually have three numbers on their markings. The major figures are the first two, and the multiplier is the third. Values are in picofarads. As a result, the SMD tantalum capacitor's value is 47 x 105pF, which equals 4.7F.As seen in the illustration below, values are often marked more directly. The markings indicate the value.SMD tantalum capacitor markings Ⅴ Applications of Tantalum CapacitorTantalum capacitors have many advantages and are used in a variety of applications, including modern electronics, where they provide higher stability over a wide range of temperatures and frequencies, long-term reliability, and record-high volumetric efficiency. Tantalum capacitors are used in applications because of their low leakage current, high capacity, and long-term stability and reliability. They're used in sample and hold circuits, for example, where a low leakage current is needed to achieve a long hold duration. Due to their small size and long-term reliability, they are often widely used for power supply filtering on computer motherboards and mobile phones, most commonly in surface-mount form.Applications of tantalum capacitorsMilitary standards (MIL-SPEC) tantalum capacitors are also available, with tighter tolerances and a wider operating temperature range. Since they do not dry out or change capacitance over time, they are a common substitute for aluminum electrolytic in military applications. Tantalum is also used in medical electronics because of its high stability. Tantalum capacitors are often used in audio amplifiers where stability is important. A tantalum capacitor is a complex component used in cardio implants to detect irregular heartbeats and deliver an electric countershock in a few seconds. Medical, telecommunications, aerospace, military, automotive, and computers are only a few of the industries that use this capacitor. Ⅵ Difference Between Tantalum and Ceramic CapacitorTantalum capacitors are used in a wide range of circuits, although they usually need an external failsafe system to prevent issues caused by their failure mode. PCs, laptops, medical equipment, audio amplifiers, automotive circuitry, mobile phones, and other surface-mounted devices are only a few examples (SMD). Tantalum electrolytic is a common alternative to aluminum electrolytic in military applications because it does not dry out or change capacitance over time. Ceramic capacitors are used in a wide range of applications, the most popular of which are personal electronic devices. MLCCs are the most widely used capacitors, accounting for around 1 billion electronic devices a year. Printed circuit boards (PCBs), induction furnaces, DC-DC converters, and power circuit breakers are some examples of applications. Since ceramic capacitors are non-polarized and come in a wide range of capacitances, voltage ratings, and sizes, they are often used as general-purpose capacitors. Tantalum Capacitors vs Ceramic CapacitorsWhile tantalum and ceramic capacitors have similar functions, their construction methods, materials, and performance are vastly different. Tantalum and ceramic capacitors vary in a few main ways when it comes to performance: • AgingWhen it comes to capacitors, aging refers to a logarithmic drop in capacitance over time. Tantalum capacitors do not age, while ceramic capacitors do. There is no known wear mechanism for tantalum capacitors. • PolarizationThe majority of tantalum capacitors are polarized. This means they can only be linked to a DC power source while maintaining proper terminal polarity. Non-polarized ceramic capacitors, on the other hand, can be safely connected to an AC source. Ceramic capacitors have a higher frequency response because they are not polarized. • Temperature ResponseTantalum capacitors have a linear capacitance change when exposed to temperature changes, whereas ceramic capacitors have a non-linear response. On the other hand, Ceramic capacitors can be made to trend linearly by narrowing the operating temperature ranges and taking temperature response into account during the design phase. • Voltage ResponseTantalum capacitors have clear capacitance changes as a function of applied voltage, whereas ceramic capacitors do not. The permittivity of the dielectric shrinks inside the ceramic capacitor in response to higher applied voltages, causing capacitance changes. While most ceramic capacitor capacitance changes are linear and easily accounted for, some higher permittivity dielectrics can lose up to 70% of their initial capacitance when operated at rated voltage.  Ⅶ FAQ1. What are the advantages and disadvantages of the tantalum capacitor?The list of the advantages and disadvantages of a solid tantalum capacitor includes the followingThe advantages are Long life, high-temperature resistance, excellent performance, high accuracy, efficiency in filtering high-frequency harmonics.The disadvantages are: Having a very thin oxide layer that is not robust, cannot withstand voltage above limits, low ripple current rating. 2. When to use a tantalum capacitor?When you need maximum capacitance in a small space like decoupling next to a microchip, excellent stability over a range of temperatures or voltages, and you are aware of their unique characteristics so they can be designed properly and not risk your system with a fiery failure. 3. What is surge voltage in terms of the tantalum capacitor?A surge voltage is the highest voltage that can be applied to a capacitor for a shorter period in circuits that has minimum series resistance. 4. What is the difference between tantalum and electrolytic capacitors?Electrolytic capacitors made with aluminum (or aluminum) are generally lower priced than those made with tantalum. Tantalum capacitors have higher capacitance per volume. Capacitors made with tantalum can be either polar and non-polar though the polarized form is more common. 5. Why do tantalum capacitors fail?A transient voltage or a current spike applied to tantalum electrolytic capacitors with solid manganese dioxide electrolyte can cause some tantalum capacitors to fail and may directly lead to a short. 6. How long do tantalum capacitors last?The capacitance stability achieved by polymer tantalum capacitors exceeds that of MLCCs over time, temperature and voltage. Whilst MLCCs are susceptible to aging, polymer tantalums achieve long-term stability over an operational lifetime of 20 years. 7. Are all tantalum capacitors polarized?Tantalum capacitors are inherently polarized components. Reverse voltage can destroy the capacitor. Non-polar or bipolar tantalum capacitors are made by effectively connecting two polarized capacitors in series, with the anodes oriented in opposite directions. 8. What is a tantalum capacitor used for?Applications using tantalum capacitors take advantage of their low leakage current, high capacity and long-term stability and reliability. For example, they are used in sample and hold circuits that rely on low leakage current to achieve long hold duration. 9. Can I replace a tantalum capacitor with an electrolytic?A tantalum capacitor is also a type of electrolytic capacitor, however, due to low leakage, they are more accurate and reliable than the cylindrical electrolytic capacitor variants. If the leakage factor is not too critical then you can easily replace a tantalum capacitor with the other regular electrolytic capacitor. 10. What is a wet tantalum capacitor?Wet tantalum capacitors are passive devices that provide capacitive reactance to circuits. They are electrolytic capacitors with a wet electrolyte, an anode and a cathode. They are used over other capacitor types due to superior characteristics including volumetric efficiency, high reliability, electrical stability over a wide temperature range and long service life. Wet tantalum capacitor technology is best suited for applications such as military, aerospace, satellites and heavy industrial application fields.

IntroductionAn analog-to-digital converter, or A/D converter, or ADC for short, usually refers to an electronic device that converts an analog signal into a digital signal. Except for the most specialized analog-to-digital converters, all ADCs are implemented as integrated circuits (ICs). These are usually mixed-signal integrated circuit chips based on metal oxide semiconductor (MOS) that integrate analog and digital circuits.As we all know, ADC is mainly used to the digital acquisition of analog signals for for data processing purposes. The signals around us are generally continuously changing analog quantities, such as light, temperature, speed, pressure, sound, etc. However, most of us use digital equipment. If we want to use and process information easily, it is necessary to convert the analog quantity into a digital quantity and transmit it to the microcontroller or microprocessor. So how is ADC conversion realized? What kind of process is it? Reading the following note, you will definitely have a more comprehensive and systematic understanding of the analog-to-digital converter.What is ADC (Analog to Digital Converter)?CatalogIntroductionⅠ A/D Converter Basic1.1 Analog-to-Digital Converter Definition1.2 Analog to Digital Conversion Steps1.3 Why do We Need Analog-to-Digital Converter?Ⅱ Which A/D Converter is Better?Ⅲ What A/D Converter Includes?Ⅳ A/D Converter Applications and ICs4.1 Analog-to-Digital Converter Applications4.2 Analog-to-Digital Converter IC Modes ExplainedⅠ A/D Converter Basic1.1 Analog-to-Digital Converter DefinitionThe ADC converter is a system that converts analog signals into digital signals. It is a process of filtering, sample-and-hold, quantization and encoding. The analog signal passes band-limited filtering, sample-and-hold circuit, and becomes a ladder-shaped signal, and then passes through the encoder to make each level in the ladder-shaped signal become a binary code. Finally, the analog quantity is converted into a digital quantity and then transmitted to the CPU. That is to say, almost all energized data need ADC conversion. For example, electric energy metering of electric energy meters, weight measurement of electronic scales, temperature measurement of electronic thermometers, and communication fields.1.2 Analog to Digital Conversion StepsThe process of converting analog quantities into digital quantities is called analog-to-digital conversion, abbreviated as A/D, and the circuit that completes this function is called analog-to-digital converter, or ADC for short.Analog-to-Digital Conversion Steps Animation1) Sampling refers to replacing the original continuous signal in time with a sequence of signal samples at regular intervals, that is, discretizing the analog signal in time.2) Quantization uses a limited number of amplitude values to approximate the original continuously changing amplitude value, that is, changing the continuous amplitude of the analog signal into a limited number of discrete values with a certain interval.3) Encoding is based on a certain rule, the quantized value is represented by binary numbers, and then converted into a binary or multi-value digital signal stream. The digital signal obtained in this way can be transmitted through digital lines such as cables, microwave trunk lines, and satellite channels.The higher the signal frequency, the higher the operating frequency of the A/D circuit. The more digits, the more accurate the restoration accuracy of the signal. The I/O port of the MCU needs program cooperation to complete the A/D conversion. What’s more, the A/D chip can also be used alone to complete the analog-to-digital conversion.1.3 Why do We Need Analog-to-Digital Converter?Computer software, radio, and digital image acquisition all need the assistance of ADC converters, that is, the wave of human digitization has promoted the invention, development and continuous change of ADC converters. In short, the ADC converter plays an important role in human digitization.1) Many recording studios use 24-bit/96 kHz (or higher) pulse code modulation (PCM) or direct stream digital (DSD) recording formats, and then use ADC samples or decimates the signal for digital audio production on discs.2) Use ADC to store or transmit almost any analog signal in digital form. For example, TV tuner cards use fast video analog-to-digital converters. Digital storage oscilloscopes require very fast analog-to-digital converters, and ADCs are also crucial for software-defined radio and its new applications.3) Digital imaging systems usually use analog-to-digital converters to digitize pixels. Some radar systems usually use ADCs to convert signal strength into digital values for subsequent signal processing.4) Certain non-electronic or only partially electronic devices (such as rotary encoders) can also be regarded as analog-to-digital converters.Figure 1. Analog to Digital Conversion Example(Light Signal to Digital Signal) Ⅱ Which A/D Converter is Better?After years of development and continuous technological innovation, ADC converters have developed from Flash ADCs, Successive-Approximation ADCs, Counting/Slope Integration ADCs to sigma-delta (Σ-Δ) ADCs and Pipelined ADCs. They have their own advantages and disadvantages, and they can also meet different requirements.Successive-Approximation ADCs, Counting/Slope Integration ADCs and compression ADCs, etc. are mainly used in low-speed or medium-speed, medium-precision data acquisition and intelligent instruments. Hierarchical and pipelined ADCs are mainly used in high-speed signal processing, fast waveform storage and data recording, etc., such as video signal quantization and high-speed digital communication technology. ∑-△ ADC is mainly used in high-precision data acquisition, especially in electronic measurement fields such as digital sound systems, multimedia, seismic exploration instruments, sonar and so on. Here a brief description of the main ADC types is given below. Successive-Approximation ADCThe successive-approximation ADC is widely used. It includes a comparator, a digital-to-analog converter, a successive-approximation register (SAR) and a control logic unit. It is to continuously compare the sampling input signal with the known voltage. One clock cycle completes the 1-bit conversion, and the N-bit conversion requires N clock cycles. The conversion is completed and the output binary number is output. The resolution and sampling rate of this type ADC are contradictory: when the ADC resolution is low, the sampling rate is high, and if the resolution is to be improved, the sampling rate will be limited.Advantages: when the resolution is lower than 12 bits, the price is cheap, and the sampling rate can reach 1MSPS. Compared with other types, the power consumption is quite low.Disadvantages: In the case of higher than 14-bit resolution, the price is higher. The signal generated by the sensor needs to be conditioned before analog-to-digital conversion, including gain stage and filtering, so that the cost will increase significantly. Counting/Slope Integration ADCsCounting/Slope Integration ADC is also called dual-slope or multi-slope ADC, and its applications are also very wide. It is composed of an analog integrator with an input switch, a comparator and a counting unit. The input analog voltage is converted into a time interval proportional to its average value through two integrations. At the same time, a counter is used to count the clock pulses in this time interval, so as to realize the analog-to-digital conversion. Because the input end applies the integrator, it has a strong ability to suppress the interference of AC noise. For example, for high-frequency noise and fixed low-frequency (50Hz or 60Hz) interference suppression, it is suitable for use in noisy industrial environments. This type ADC is mainly used in low-speed, precision measurement and other fields, such as digital voltmeters.Advantages: High resolution, up to 22 bits; low power consumption and low cost.Disadvantages: The conversion rate is low, 100~300SPS at 12 bits. Parallel ADCsThe main feature of inter ADC is fast speed, which is the fastest of all types. The sampling rate can reach above 1GSPS. However, due to the limitations of power and volume, it is difficult to improve the resolution. The conversion of all bits of the ADC with this structure is completed at the same time, and the conversion time mainly depends on the switching speed of the comparator and the transmission time delay of the encoder. In addition, increasing the output code has little effect on the conversion time, but as the resolution increases, a high-density analog design  requires large number of precision divider resistors and comparator circuits for the conversion. That is to say, the output number is increased by one bit and the number of precision resistors is increased. It is about to double, and the comparator is also approximately doubled.The resolution of the parallel comparison ADC is limited by die size, input capacitance, power, etc. If the accuracy of the parallel comparators does not match, it will also cause static errors and increase the input offset voltage. Sigma-delta (Σ-Δ) ADCsThe Sigma-delta (Σ-Δ) ADC is composed of an integrator, a comparator, a 1-bit DA converter, and a digital filter. In principle, it is similar to the integral type. The input voltage is converted into a time (pulse width) signal and processed by a digital filter to obtain a digital value.Figure 2. Analog to Digital Converter Application ExampleⅢ What A/D Converter Includes?1) Sampling RateThe sampling rate indicates the rate at which the analog signal is converted into a digital signal, which is related to the manufacturing technology of the ADC device and depends on the judgment ability provided by the comparator in the ADC.Generally speaking, the sampling rate and resolution are mutually restrictive. Each time the sampling rate is doubled, the resolution losses 1bit. This is mainly due to the jitter during sampling, that is, aperture jitter or aperture uncertainty. 2) ADC ResolutionThe resolution indicates the number of bits after the analog signal is converted into a digital signal. It directly determines the quantization level of the ADC, that is, the minimum analog signal level value that the ADC can distinguish. Assuming that the ADC's input voltage range is (−V, V) and the resolution is N (bit), then the ADC has a 2N quantization level, so that the quantization level is: ΔV=2V/2N, where ΔV is the conversion accuracy. It can be seen from the above formula that the higher the resolution of the ADC and the smaller the voltage input range, the higher its conversion accuracy. 3) Signal-to-Noise Ratio (SNR)The signal-to-noise ratio (SNR) of the ADC reflects the ratio of the root mean square value of the noise-free signal part generated during the quantization process to the root mean square value of the quantization noise. If the input signal is a normalized sine wave 1/2sin(ωt+ψ), the SNR can be determined by the following formula: Among them, N is the resolution of ADC. It can be seen that the signal-to-noise ratio of the ADC mainly depends on the resolution. Every time the resolution increases by one bit, the SNR will increase by 6dB. However, as the resolution increases, the quantization level of the ADC becomes smaller, and the sampling process is more likely to be disturbed. 4) Effective Number of Bits (ENOB)ENOB is a measure of the dynamic range of an ADC converter. For the actual A/D conversion system, due to the influence of factors such as electrical noise, external interference, and non-linear distortion of analog circuits, it is not enough to measure system performance with ideal resolution. In order to better reflect the system performance, on the basis of the measured SNR, the above factors can be converted into quantization noise to get the ENOB. The calculation formula is as follows: ENOB is based on the equation for an ideal ADC's SNR: SNR = 6.02 × N + 1.76 dB, where N is the ADC's resolution.The difference between ENOB and ADC resolution reflects the degree of decrease in sampling accuracy caused by the decrease in SNR(here SNR caused by the error source). 5) Non-Linearity ErrorNon-linear error is an important accuracy index of the converter, which represents the difference between the actual conversion value of the ADC and the theoretical conversion value. Non-linear errors mainly include two types: Differential Non-Linearity (DNL) errors and Integral Non-Linearity (INL) errors. 6) Inter Modulation Distortion (IMD)When two sinusoidal signals are input to the ADC at the same time, due to the nonlinearity of the device, except the components of these two frequencies, the output spectrum will also produce many distortion products. The resulting distortion is called inter modulation distortion ( IMD, Inter Modulation Distortion), where the value of m+n represents the order of distortion. Among all inter-modulation distortions, the second-order and third-order inter-modulation products are the most important. The former is easily filtered out by a digital filter, while the latter is difficult to filter out. 7) Total Harmonic Distortion (THD)Due to the nonlinearity of the ADC, many high-order harmonics of the input signal appear in the output spectrum. These high-order harmonic components are called harmonic distortion components, and the resulting distortion is called Total Harmonic Distortion. Harmonic distortion and modulation distortion are two different concepts. The former is a distortion of the original signal waveform, even if a single frequency signal passes through the ADC, this phenomenon will occur, while the latter is mutual interference and influence between different frequencies.Figure 3. ADC on the ArduinoⅣ A/D Converter Applications and ICs4.1 Analog-to-Digital Converter ApplicationsMost ADC applications today belong to Four Segments: (a) Data acquisition(b) Precision industrial measurement(c) Voiceband and audio(d) High speed (sampling rates greater than about 5 MSPS)4.2 Analog-to-Digital Converter IC Modes ExplainedThere are many ADC ICs available in the market which can be used along to do conversion. Here lists several ADC ICs and their features and specifications as ADC selection references.⭕AD762116-Bit, 2 LSB INL, 3 MSPS PulSAR® ADC, High sampling rate, Available in a 48-lead LQFP or a 48-lead LFCSP⭕AD764118-Bit, 2 MSPS, Charge Redistribution SAR ADC 16 Bits Resolution with No Missing CodesNo Pipeline Delay ( SAR architecture )Differential Input Range: ±VREF (VREF up to 2.5V)Throughput:  3 MSPS (Wideband Warp and Warp Mode)  2 MSPS (Normal Mode)  1.25 MSPS (Impulse Mode)INL ±2 LSB Max (±30 ppm of FS)SINAD: 89 dB Typ @ 100 kHzTHD: -103 dB Typ @ 100 kHzParallel (16 or 8 bits bus) and Serial 5 V/3.3 V/2.5 V InterfaceSPI®/QSPI™/MICROWIRE™/DSP CompatibleOn-board Low Drift Reference with Buffer and Temperature SensorSingle 2.5 V Supply OperationPower Dissipation: 70 mW Typ @ 3 MSPS With REF18-bit resolution with no missing codes2.5 V internal low drift referenceThroughput:  2 MSPS (Warp mode)  1.5 MSPS (Normal mode)Differential input range: ± VREF (VREF up to 2.5 V)INL: ±2 LSB typicalNo pipeline delay (SAR architecture)Parallel (18-, 16-, or 8-bit bus)Serial 5 V/3.3 V/2.5 V interfaceSPI®/QSPI™/MICROWIRE™/DSP compatibleOn-board low drift reference with buffer and temperature sensor ⭕AD79088-Channel, 1 MSPS, 8-Bit ADC with Sequencer in 20-Lead TSSOP⭕AD79188-Channel, 1 MSPS, 10-Bit ADC with Sequencer in 20-Lead TSSOPFast throughput rate: 1 MSPSSpecified for AVDD of 2.7 V to 5.25 VLow Power:  6.0 mW max at 1 MSPS with 3 V supply  13.5 mW max at 1 MSPS with 5 V supplyEight (single-ended) inputs with sequencerWide input bandwidth: AD7928, 70 dB min SINAD at 50 kHz input frequencyFlexible power/serial clock speed managementNo pipeline delaysHigh speed serial interface SPI®/QSPI™/MICROWIRE™/DSP compatibleFast throughput rate: 1 MSPSSpecified for AVDD of 2.7 V to 5.25 VLow Power:  6.0 mW max at 1 MSPS with 3 V supply  13.5 mW max at 1 MSPS with 5 V supplyEight (single-ended) inputs with sequencerWide input bandwidth: AD7928, 70 dB min SINAD at 50 kHz input frequencyFlexible power/serial clock speed managementNo pipeline delaysHigh speed serial interface SPI®/QSPI™/MICROWIRE™/DSP compatible ⭕AD79288-Channel, 1 MSPS, 12-Bit ADC with Sequencer in 20-Lead TSSOP⭕AD5555Precision DUAL 16-Bit 14-Bit-DACs in Compact TSSOP PackagesFast throughput rate: 1 MSPSSpecified for AVDD of 2.7 V to 5.25 VLow Power:  6.0 mW max at 1 MSPS with 3 V supply  13.5 mW max at 1 MSPS with 5 V supplyEight (single-ended) inputs with sequencerWide input bandwidth: AD7928, 70 dB min SINAD at 50 kHz input frequencyFlexible power/serial clock speed managementNo pipeline delaysHigh speed serial interface SPI®/QSPI™/MICROWIRE™/DSP compatible14-bit resolution±1 LSB DNL monotonic±1 LSB INL2 mA full-scale current ±20%, with VREF = 10 V0.5 μs settling time2Q multiplying reference-input 6.9 MHz BWZero or midscale power-up presetZero or midscale dynamic reset3-wire interfaceCompact TSSOP-16 package ⭕AD823016 V Rail-to-Rail, Zero-Drift, Precision Instrumentation Amplifier⭕AD77993-Channel, Low Noise, Low Power, 24-Bit, Sigma Delta ADC with On-Chip In-AmpResistor programmable gain range: 101 to 1000Supply voltage range: ±4 V to ±8 VRail-to-rail input and outputMaintains performance over −40°C to +125°CExcellent ac and dc performance  110 dB minimum CMR @ 60 Hz, G = 10 to 1000  10 μV maximum offset voltage (RTI, ±5 V operation)  50 nV/°C maximum offset drift  20 ppm maximum gain nonlinearityRMS noise:  27 nV at 4.17 Hz (AD7799)  65 nV at 16.7 Hz (AD7799)  40 nV at 4.17 Hz (AD7798)  85 nV at 16.7 Hz (AD7798)Current: 380 μA typicalPower-down: 1 μA maximumLow noise, programmable gain, instrumentation ampUpdate rate: 4.17 Hz to 470 Hz 3 differential inputsInternal clock oscillatorSimultaneous 50 Hz/60 Hz rejectionReference detectLow-side power switchProgrammable digital outputsBurnout currentsPower supply: 2.7 V to 5.25 V ⭕AD944414-Bit, 80 MSPS A/D Converter⭕AD944514-Bit, 105 MSPS / 125 MSPS A/D Converter80 MSPS guaranteed sampling rate100 dB two-tone SFDR with 69.3 MHz and 70.3 MHz73.1 dB SNR with 70 MHz input97 dBc SFDR with 70 MHz inputExcellent linearity  DNL = ±0.4 LSB typical  INL = ±0.6 LSB typical1.2 W power dissipation3.3 V and 5 V supply operation2.0 V p-p differential full-scale inputLVDS outputs (ANSI-644 compatible)Data format selectOutput clock available125 MSPS guaranteed sampling rate (AD9445BSV-125)100 dB two-tone SFDR with 30 MHz and 31 MHz73.5 dB SNR with 70 MHz input85 dBc SFDR with 225 MHz inputExcellent linearity  DNL = ±0.25 LSB typical  INL = ±0.8 LSB typical2.3 W power dissipation3.3 V and 5 V supply operation2.0 V p-p to 3.2 V p-p differential full-scale inputLVDS outputs (ANSI-644 compatible) or CMOS outputsData format select (Offset Binary or 2’s compliment)Output clock available ⭕AD944616-Bit, 80 MSPS / 100 MSPS A/D Converter⭕AD923512-Bit, 20/40/65 MSPS, 3 V Analog-to-Digital Converter100 MSPS guaranteed sampling rate (AD9446-100)83.6 dBFS SNR with 30 MHz input(3.8 V p-p input, 80 MSPS)82.6 dBFS SNR with 30 MHz input(3.2 V p-p input, 80 MSPS)89 dBc SFDR with 30 MHz input(3.2 V p-p input, 80 MSPS)95 dBFS 2-tone SFDR with 9.8 MHz and10.8 MHz (100 MSPS)l 60 fsec rms jitterExcellent linearity  DNL = DNL = ±0.4 LSB typical  INL = ±3.0 LSB typical2.0 V p-p to 4.0 V p-p differential full-scale inputBuffered analog inputsLVDS outputs (ANSI-644 compatible) or CMOS outputsData format select (offset binary or twos complement)Output clock available3.3 V and 5 V supply operationSingle +3 V Supply Operation (2.7 V to 3.6 V)SNR = 70 dBc to Nyquist at 65 MSPSSFDR = 85 dBc to Nyquist at 65 MSPSLow Power: 300 mW at 65 MSPSOn-Chip Reference and SHADifferential Input with 500 MHz BandwidthDNL of ±0.4 LSBFlexible Analog Input: 1 V p-p to 2 V p-pOffset Binary or Twos Complement Data FormatClock Duty Cycle StabilizerPin out Migration to Either AD9215, AD9236, AD9245 Frequently Asked Questions about Analog to Digital Converter (ADC Basic)1. What is the use of analog to digital converter?Analog-to-digital converters, abbreviated as “ADCs,” work to convert analog (continuous, infinitely variable) signals to digital (discrete-time, discrete-amplitude) signals. In more practical terms, an ADC converts an analog input, such as a microphone collecting sound, into a digital signal. 2. What are the types of analog to digital converters?There are really five major types of ADCs in use today:Successive Approximation (SAR) ADCDelta-sigma (ΔΣ) ADCDual Slope ADCPipelined ADCFlash ADC 3. Which chip is used in analog to digital?An A/D converter is used to convert an analog signal like voltage to digital form so that it can be read and processed by a microcontroller. Some microcontrollers have built-in A/D converters. It is also possible to connect an external A/D converter to any type of microcontroller. 4. Which circuit is used in analog to digital converter?Analog to Digital Converter (ADC) is an electronic integrated circuit used to convert the analog signals such as voltages to digital or binary form consisting of 1s and 0s. Most of the ADCs take a voltage input as 0 to 10V, -5V to +5V, etc., and correspondingly produces digital output as some sort of a binary number.

IntroductionA voltage regulator is a circuit that generates a fixed output voltage of a preset magnitude that remains constant regardless of changes to its input voltage or load conditions. It converts an unstable dc voltage into a stable dc voltage. Its power supply composed of discrete components has the advantages of large output power and wide adaptability. In recent years, integrated regulated power supplies have been widely used. Among them, three-terminal series regulators are the most common for low-power regulated power supplies. The commonly used integrated voltage regulators in the circuit mainly include 78xx series, 79xx series, adjustable integrated voltage regulator, precision voltage reference integrated voltage regulator, etc.What is a Voltage Regulator and How Does It Work?CatalogIntroductionⅠ Voltage Regulator ClassificationⅡ Main ParametersⅢ Applying NotesⅣ Typical Examples: LM317 & LM7805Ⅰ Voltage Regulator ClassificationVoltage regulators are generally divided into linear voltage regulator and switching voltage regulator. Linear voltage regulator is a circuit used to maintain a steady voltage, which is divided into low dropout type and general dropout type. Switching voltage regulator is a type of switch mode power supply circuit that is designed to efficiently reduce dc voltage from a higher voltage to a lower one, which is divided into step-down type, step-up type and integrated type with opposite input and output polarity.According to the number of outlet terminals and usage of the voltage regulator, it can be roughly divided into three-terminal fixed type, three-terminal adjustable type, multi-terminal adjustable type and single-chip switch type.The three-terminal fixed type voltage regulator integrates sampling resistors, compensation capacitors, protection circuits, high-power adjustment tubes, etc. on a chip. So that the entire integrated circuit block has only 3 terminals: input, output and public. It is very convenient to use. Its disadvantage is that the output voltage is fixed, so a series of products with various output voltages and current specifications must be produced to match.The three-terminal adjustable integrated voltage regulator only needs two external resistors to obtain various output voltages.The multi-terminal adjustable type is an early integrated voltage regulator. With small output power and many pins, it is not convenient to use, but the precision is high and the price is cheap.The monolithic switch type integrated regulated power supply develops in recent years, and its efficiency is particularly high. Its working principle is different from the above three types. It is a converter that converts DC to AC (high frequency) and then DC. Usually there are two types of pulse width modulation and pulse frequency modulation, and the output voltage is adjustable.Ⅱ Main Parameters1) Voltage Regulation RateIt is an important indicator that characterizes the voltage regulation performance of the integrated voltage regulator, also known as the voltage regulation coefficient or stability. It represents how stable the output voltage V0 of the regulator is when the input voltage V1 changes.2) Current Regulation RateIt is also known as current stability coefficient, and shows the ability of the regulator to suppress output voltage fluctuations caused by changes in load current (output current) when the input voltage remains unchanged.3) Ripple Rejection RatioIt reflects the ability of the regulator to suppress the mains ripple voltage introduced at the input.4) Output Voltage Temperature CoefficientIt is also known as the output voltage temperature change rate, and refers to when the input voltage and output current (load current) remain unchanged, the output voltage of the regulator changes with temperature.5) Long-term Stability of the Output VoltageIt refers to the magnitude of the change in the output voltage value over time (when the output current, input voltage and ambient temperature remain unchanged). It is usually the maximum amount of change in the output voltage of the regulator within a specified time.6) Output Noise VoltageIts absolute value represents the noise performance of the regulator directly. There is also a percentage value of the output noise voltage Vn and the output voltage V0 of the regulator to characterize the noise performance.7) Thermal StabilityIt refers to the thermal stability of the voltage regulator. It is usually the percentage value of the relative change in the output voltage caused by its unit power consumption.8) Temperature StabilityIt is the percentage value of the relative change of the regulator's output voltage within the specified maximum change range of operating temperature. Ⅲ Applying Notes① There are many types of integrated voltage regulator. According to the adjustment method there are linear and switch type. Based on the output method, there are fixed and adjustable types. Because of the obvious advantages of the three-terminal voltage regulator, it is more convenient to use and operate.② Before connecting to the circuit, it is necessary to distinguish the pins and their functions to avoid damage to the integrated block. The input and output ends of the three-terminal integrated voltage regulator with an output voltage greater than 6v need to be connected with protective diodes to prevent the rapid discharge of the output capacitor, which will cause damage to the three-terminal integrated voltage regulator when the input voltage drops suddenly.③ In order to ensure the stability of the output voltage, the minimum input voltage difference should be guaranteed. For example, the minimum pressure difference of the three-terminal integrated voltage regulator is about 2v, and it should be kept above 3v during general use. At the same time, it should be noted that the maximum voltage difference of input and output does not exceed the specified range.④ In order to expand the output current, the three-terminal integrated voltage regulator is allowed to be used in parallel.⑤ When using, the welding should be firm and reliable. If a heat dissipation device is required, it should meet the required size.If you have a bad regulator, it may cause many components such as the fuel pump, ignition system, or other parts which require a minimum amount of voltage to not function correctly. You may experience the engine sputtering, a rough idle, or simply a lack of acceleration when you need it. Ⅳ Typical Examples: LM317 & LM7805The LM317 device is an adjustable three-terminal positive-voltage regulator capable of supplying more than 1.5 A over an output-voltage range of 1.25V to 37V. It serves a wide variety of applications including local, on card regulation. This device can also be used to make a programmable output regulator, or by connecting a fixed resistor between the adjustment and output, the LM317 can be used as a precision current regulator.LM317 Specifications Adjustable output voltage as low as 1.2VOutput voltage: 1.25-37V DCGuaranteed 1.5A output currentOutput current: 5mA-1.5ATypical linear adjustment rate: 0.01%Max input-output voltage difference: 40V DCTypical load regulation rate: 0.1%Min input-output voltage difference: 3V DCRipple rejection ratio: 80dBOperating temperature: -10± 85℃Output short circuit protectionStorage temperature: -65± 150℃Over-current, overheat protectionOutput voltage: 1.25-37V DCAdjusting tube safe working area protectionOutput current: 5mA-1.5A The linear voltage regulator LM7805 has over-voltage protection, over-current protection, and over-heat protection functions, which makes its performance very stable. It is a 5V regulator, and is able to achieve output current above 1A, and has a good temperature coefficient. So the product has a wide range of applications. Have a look to get more specific info by the following video:Why is the LM7805 is a very Popular Voltage Regulator?As a member of 78xx series of fixed linear voltage regulators, the following is a very good summary of the basics on linear voltage regulator 7805:ParameterSymbolConditionsMinTypicalMaxUnitOutput VoltageVoTj=25℃4.85.05.2V5.0mA<Io<1.0APo<15WVi=7v to 20v4.755.05.25VLinear Adjustment rate△VlineTj=25℃, Vi=7V to 25V 3.0100mVTj=25℃Vi=8V to 12V 1.050mVLoad Adjustment Rate△VloadTj=25℃,lo=5.0mA to 1.5A  100mVTj=25℃lo=250mA to 750mA  50mVStatic CurrentIqTj=25℃  8mAStatic Current Rate△Iqlo=5mA to 1.0A  0.5mAVi=7V to 25V  0.8mAOutput Voltage Drift△Vo/△Tlo=5mA -1.1 mV/℃Output Noise VoltageENf=10Hz to 100KHzTj=25℃  40μV/VoRipple Rejection RatioSVRf=120Hz,Vi=8V to 18V62  dBVoltage DifferentialVdlo=1.0ATj=25℃ 2.0 VOutput ImpedanceRof=1KHz 17 mΩShort-circuit CurrentIscVi=35VTj=25℃ 750 mAPeak CurrentIscpTj=25℃ 2.2 AIf you want to make a 5V power supply with a 7805, output currents up to 1A can be drawn from the IC provided that there is a proper heat sink. A 9V transformer steps down the main voltage, 1A bridge rectifies it and capacitor C1 filters it and 7805 regulates it to produce a steady 5V DC. Then you can test it, turn on the DC power supply and adjust the output voltage of about 8V or slightly larger. Or alternatively you can use a battery 9V-12V as voltage source. Look at the voltmeter panel when you set the voltage. Prepare a DC voltmeter readings on voltage range 50V to measure the output voltage of the IC 7805. Frequently Asked Questions about Voltage Regulator1. What is voltage regulator and how it works?A voltage regulator generates a fixed output voltage of a preset magnitude that remains constant regardless of changes to its input voltage or load conditions. ... A switching regulator converts the dc input voltage to a switched voltage applied to a power MOSFET or BJT switch. 2. What is a voltage regulator used for?Voltage regulator, any electrical or electronic device that maintains the voltage of a power source within acceptable limits. The voltage regulator is needed to keep voltages within the prescribed range that can be tolerated by the electrical equipment using that voltage. 3. What are the three 3 basic types of voltage regulators?There are three types of Switching voltage regulators: Step up, Step down, and Inverter voltage regulators. 4. What happens when voltage regulator goes bad?If you have a bad regulator, it may cause many components such as the fuel pump, ignition system, or other parts which require a minimum amount of voltage to not function correctly. You may experience the engine sputtering, a rough idle, or simply a lack of acceleration when you need it. 5. Where are voltage regulators used?Electronic voltage regulators are found in devices such as computer power supplies where they stabilize the DC voltages used by the processor and other elements. In automobile alternators and central power station generator plants, voltage regulators control the output of the plant.