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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.

IntroductionThe operational amplifier is an integrated circuit that has two input pins and one output pin. It is used to amplify and output the voltage difference between the two input pins. Based on its characteristics, operational amplifier has different functions in different circuits. Here introduces common and fundamental op amp circuits examples with descriptions.A Basic Introduction to Op Amp CircuitsCatalogIntroductionOp Amp Diagram and Circuit Analysis1.1 What is the Inverting & Non-inverting Amplifier?1.2 Differential Amplifier1.3 Summing Amplifier1.4 Practical Differentiator1.5 Op-amp Integrator1.6 Converter, Detector, Bias Current Compensation, Voltage Comparator1.7 Offset Voltage Adjustment1.8 Sine Wave Generator1.9 Op-Amp Voltage Reference1.10 Instrumentation Amplifier1.11 Precision Current Sink & Source1.12 Precision Diode & Clamp1.13 Notch Filter Amplifier1.14 Capacitance Multiplier2 Other Op-amp Circuit ApplicationsOp Amp Diagram and Circuit AnalysisHow do you build an op amp circuit? This part introduces the most basic operational amplifier circuits. Understand the role of op amp in different circuits, and do reference design for your own amplifier circuit through the description of the op amp equations. What’s more, you can handle the most common op amp applications through these circuits.1.1 What is the Inverting & Non-inverting Amplifier?Figure 1. Inverting AmplifierIn an inverting amplifier circuit, the operational amplifier inverting input receives feedback from the output of the amplifier. Assuming the op-amp is ideal and applying the concept of virtual short at the input terminals of op-amp, the voltage at the inverting terminal is equal to non-inverting terminal. Figure 2. Inverting Amplifier with High Input ImpedanceIn electronics, high impedance means that a point in a circuit (a node) allows a relatively small amount of current through. For an inverting amplifier, the input impedance is approximately equal to the input resistance. This is because the input resistor is connected to “virtual ground” in the inverting configuration.Another Example:Figure 3. Fast Inverting Amplifier with High Input Impedance Figure 4. Non-inverting AmplifierA non-inverting amplifier is an op-amp circuit configuration which produces an amplified output signal. This output signal of non-inverting op amp is in-phase with the input signal applied. In other words a non-inverting amplifier behaves like a voltage follower circuit.Another Example:Figure 5. Non-inverting AC AmplifierRecommended Readings: Inverting and Non-inverting Amplifier and Their Basics......(1)Op Amp High Input Impedance and Low Output Impedance......(2)1.2 Differential AmplifierFigure 6.The differential amplifier circuit is a very useful op-amp circuit and by adding more resistors in parallel with the input resistors. It usually has two outputs and two inputs, which is a special purpose amplifier designed to measure differential signals, otherwise known as a subtractor. 1.3 Summing AmplifierThe Summing Amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage.Example Explained:Figure 7. Fast Summing Amplifier with Low Input Current Figure 8. Inverting Summing AmplifierThe inverting summing amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage. When the summing point is connected to the inverting input of the op-amp the circuit will produce the negative sum of any number of input voltages. Figure 9. Non-inverting Summing AmplifierThe non-inverting summing amplifier is a similar configuration to the inverting summing amplifier. In other words, it is based around the configuration of a non-inverting operational amplifier circuit in that the input (either ac or dc) is applied to the non-inverting (+) terminal, while the required negative feedback and gain is achieved by feeding back some portion. 1.4 Practical DifferentiatorFigure 11.A practical differentiator amplifier is basically a high pass filter and are used in wave shaping circuits, frequency modulators etc. Because 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. In other words, the circuit behaves like a high-pass filter. 1.5 Op-amp IntegratorAn op-amp integrator is an electronic integration circuit that performs the mathematical operation of Integration, that is we can cause the output to respond to changes in the input voltage over time as the op-amp integrator produces an output voltage which is proportional to the integral.Figure 12. Fast Integrator Figure 13. Fast Integrator with Low Input Current Figure 14. Low Drift IntergratorIn Low Drift Intergrator circuit, the output of an operational amplifier always contains signals that could not have been predicted, even with knowledge of the input and an accurately. 1.6 Converter, Detector, Bias Current Compensation, Voltage ComparatorFigure 15. Current to Volatge ConverterA current to voltage converter will produce a voltage proportional to the applied input current. This circuit is required if your measuring instrument is capable only of measuring voltages and you need to measure the current output. Figure 16. Precision AC to DC ConverterA simple full wave precision rectifier using a single supply operational amplifier in saturation mode, which is to insure precision half wave rectification and unidirectional current flow. Figure 17. Temperature Compensated Logarithmic ConverterA temperature compensated logarithmic amplifier for signal strength indicator or automatic gain control applications is presented.  Figure 18. Double-Ended Limit DetectorThe circuit in see a differential Input to single ended output amplifier will convert a differential (double ended) signal. Figure 19. Fast Zero Crossing DetectorA zero-crossing detector whose input is a sign wave has been converted into a train of positive pulses at interval T by adding a RC network and a clipping. It can be used to detect phase anomalies, or even as a 'loss of AC' detector, purposes of synchronization, fast and accurate frequency. Figure 20. Low Drift Peak DetectorOp-amp based peak detector circuit is the modification of basic peak detector circuit, used to remove the voltage drop across the diode. It stores the peak value of input voltages for infinite time duration until it comes to reset condition. Figure 21. Op Amp Integrator with Bias Current CompensationThe operational amplifier integrator is an electronic integration circuit, where the resistor producing a compensating current flow through the series capacitor to maintain the virtual ground. Figure 22. Voltage Comparator for Driving DTL or TTL Integrated CircuitHigh frequency performance at any gain as a comparator the output can be drived DTL or TTL integrated circuit. Figure 23. Threshed Detector for PhotodiodesUse operational amplifiers or op-amps to convert the photodiode current to a measurable voltage. 1.7 Offset Voltage AdjustmentThe input offset voltage is defined as the voltage that must be applied between the two input terminals of the op amp to obtain zero volts at the output. Ideally the output of the op amp should be at zero volts when the inputs are grounded. The presence of offset can be encapsulated by assuming that the real Op Amp input/output transfer characteristic is y = A (V + – V – + e ) where e is the error in the differential input to the ideal Op Amp.Figure 24. Offset Voltage Adjustment for Inverting Amplifiers Using Any Type of Feedback Element Figure 25. Offset Voltage Adjustment for Non-inverting Amplifiers Using Any Type of Feedback Element Figure 26. Offset Voltage Adjustment for Voltage Followers Figure 27. Offset Voltage Adjustment for Differential Amplifiers Figure 28. Offset Voltage Adjustment for Inverting Amplifiers Using 10kΩ Source Resistance or Less 1.8 Sine Wave GeneratorSine Wave Generator Using Op AmpThe Sine Wave Generator is a type of electronic equipment that generates an oscillating frequency in a sinusoidal pattern. One of the popular methods of generating a sine wave with an operational amplifier is to use the Wien bridge configuration.Figure 29. Low Frequency Sine Wave Generator with Quadrature Output Figure 30. High Frequency Sine Wave Generator with Quadrature Output 1.9 Op-Amp Voltage ReferenceA voltage reference, or a VREF, is a precision device designed to maintain an accurate, low noise, constant output voltage. Ideally, the output should remain constant even as parameters, such as ambient temperature, supply voltage, or the load current change.Figure 31. Positive Voltage ReferenceIn a positive voltage reference a non-inverting op-amp buffer is often included to scale the output voltage and supply any current needed. Figure 32. Negative Voltage ReferenceA common way to generate a negative voltage has been to use an operational amplifier (op amp) to invert the output of a positive precision voltage reference. This approach typically requires a positive reference, the op amp, and two supply rails to generate the negative output. 1.10 Instrumentation AmplifierInstrumentation amplifier is a kind of differential amplifier with additional input buffer stages. It is a differential op-amp circuit providing high input impedance with ease of gain adjustment. Basically, a typical Instrumentation Amplifier configuration consists of three Op-amps and several resistors.Figure 33. Differential-input Instrumentation Amplifier Figure 34. Variable Gain, Differential-input Instrumentation Amplifier Figure 35. Instrumentation Amplifier with ±100V Common Mode Range Figure 36. Instrumentation Amplifier with ±10V Common Mode Range Figure 37. High Input Impedance Instrumentation Amplifier 1.11 Precision Current Sink & SourceOp Amp can source or sink current.Sourcing current means that current is flowing out of the op-amp into the load. Sinking current means that current is flowing in to the op-amp.Figure 38. Precision Current SinkFor a current sink circuit, opamp are designed to be used in both positive and negative voltages. The op-amp connection is changed, that is the negative input is connected to a shunt resistor. Figure 39. Precision Current SourcePrecision current sources have traditionally been built using op amps, resistors, and other discrete components—with limitations due to size, accuracy. Figure 40. Bilateral Current Source 1.12 Precision Diode & ClampFigure 41. Precision DiodeIn this circuit , the op-amp circuit is required to work as an ideal diode. That is, an ideal op-amp wants to make its two inputs equal in voltage through the negative feedback path. Figure 42. Precision ClampPrecision Op-Amp Clamp Circuit is the same circuit as the classic simple precision rectifier (set to pass the negative half-sine), but with the non-inverting input of the op-amp. 1.13 Notch Filter AmplifierNotch filter is a useful circuit to suppress middle- and high-frequency resonance to improve control precision. It work on only a narrow band of frequencies. To be useful, the notch filter must be tuned to the frequency of resonance or of noise generation.Figure 43. Adjustable Q Notch Filter Figure 44. Easily Tuned Notch Filter 1.14 Capacitance MultiplierCapacitance Multiplier uses an op-amp and a small capacitor to simulate a much larger capacitor instead of a transistor.Example Explained:Figure 45. Negative Capacitance Multiplier Figure 46. Variable Capacitance Multiplier Figure 47. Analog MultiplierIn electronics, an analog multiplier is a device which takes two analog signals and produces an output which is their product. Analog multipliers take two or more analog signals and produce an output which is their product or the sum of multiple products. 2 Other Op-amp Circuit DesignFigure 48. Free-Running MultivibratorThe Op-amp Multivibrator is an astable oscillator circuit that generates a rectangular output waveform using an RC timing network connected to the inverting end. An astable multivibrator uses an op-amp. It generates square waves of its own i.e. without any external excitation. Figure 49. Op Amp Function GeneratorFunction generator system can be readily synthesized using operational amplifiers on an approach which uses full when the need for a special need. Figure 50. Pulse-width Modulator (PWM)Pulse-width Modulator is a way to control analog devices with a digital output. It uses digital signals to control power applications, as well as being fairly easy to convert back to analog with a minimum of signal. High-frequency op amps can be used for a high-frequency PWM, because op amps are used for the modulator. Bridge AmplifierThe bridge amplifier is to generate both an inverted and a noninverted output signal. When the amplifier is switched into bridge-mode operation, the signal at the output of the first stage of amplification of channel A is attenuated. In addition, bridging an amplifier refers to the process of combining two of four channels into one or two channels with half the ohms.Figure 51. Bridge Amplifier with Low Noise Compensation Figure 52. Wien Bridge Sine Wave OscillatorA Wien bridge oscillator is a simple circuit that can be set to continuous oscillation, which outputs a sine wave. It acts as a useful reference oscillator for analog circuits, and the output signal can then be manipulated with other analog circuits. It is an excellent circuit for generating a sine wave signal at audio frequencies. Figure 53. Low Power Supply for Intergrated Circuit TestingOp-amp IC Testing Circuit basically has voltage comparator inside, which has two inputs, one is inverting input and second is non-inverting input. In normal, putting a good op-amp into the circuit, and they will generate a low frequency in the square wave. Figure 54. Fast Half Wave RectifierPrecision half-wave rectifiers are commonly used with other op amp circuits such as a peak-detector or bandwidth limited non-inverting amplifier to produce a DC output voltage. For the positive half cycle of the sinusoidal input, the output of the op-amp will be negative. Figure 55. Absolute Value Amplifier with Polarity DetectorAbsolute Value Amplifier with Polarity Detector Circuit breaks an input voltage signal down into its components. It will handle direct input voltages as well as alternating voltages up to several kHz. Figure 56. Sample and Hold Circuit Using Op AmpIn electronics, a sample and hold (also known as sample and follow) circuit is an analog device that samples (captures, takes) the voltage of a continuously varying analog signal and holds (locks, freezes) its value at a constant level for a specified minimum period of time. It consists of switching devices, capacitor and an operational amplifier. Figure 57. Tuned CircuitA tuned circuit has a very high impedance at its resonant frequency (ideally = infinity). At other frequencies, its impedance is lower. Tuned circuits are used to select or tune in radio stations on a particular frequency and reject all the others. When an amplifier circuit has its load replaced by a tuned circuit, such an amplifier can be called as a tuned amplifier circuit. It is generally referred to as active filters.Another Example:Figure 58. Two-Stage Tuned Circuit Figure 59. Simulated InductorA simulated inductor is an active circuit for generating an equivalent inductive reactance, which is implemented with active and passive components. It is used in the design of filters, amplifiers, oscillators and tuned amplifiers. Figure 60. High Pass Active FilterA high-pass filter (HPF) is an electronic filter that passes signals with a frequency higher than a certain cutoff frequency and attenuates signals with low frequencies. Active High Pass Filter uses inverting operational amplifier with high voltage gain. Figure 61. Low Pass Active FilterA simple active low pass filter is formed by using an op-amp. The operational amplifier will take the high impedance signal as input and gives a low impedance signal as output. The circuit uses an op-amp for amplification and gain control. Figure 62. Nonlinear OP AMP with Temperature Compensated BreakpointsAs long as the gain of the operational amplifier is large enough, the amplification of the circuit is determined by the external feedback resistance network. Figure 63. Current MonitorA current monitor amplifier is a special purpose integrated circuit differential amplifier that is designed to sense the voltage developed across a current shunt and output a voltage proportional to the measured current. Figure 64. Power Booster AmplifierA power booster amplifier is typically a hybrid circuit with thick film resistors, ceramic capacitors. A novel power booster amplifier is based on a modified half-bridge topology using separated switches and a floating bridge capacitor. Figure 65. Long Interval TimerWith the help of high gain high impedance operational amplifier, we can build a long time delay with resistor-capacitor (RC) circuit. Figure 66. Amplifier for Piezoelectric TransducerThe charge sensitive amplifiers employed for piezo electric sensors cover quite wide range. Piezoelectric transducers used as sensors, typically, the high impedance of the sensor requires an amplifier. Figure 67. Temperature ProbeAn inverting op amp operates with a noise gain of two, which produces twice as much output offset voltage as does a unity-gain buffer. This is a fantastic solution to temperature monitoring. Figure 68. Photodiode AmplifierPhotodiode amplifier circuit pedance amplifier for amplifying the light- dependent current of a photodiode. The high gain of the op-amp keeps the photodiode current equal to the feedback current. Some are ideally suited for ultra low noise amplification of very small photodiode currents. Figure 69. High Input Impedance AC FollowerOperational amplifiers have a very high input impedance, which means that they don't suck in much current (ideally, none) at the inputs, typically above 1MΩ as it is equal to that of the operational amplifiers input resistance. Low output impedance and extremely high input impedance make it a simple and effective solution to problematic impedance. Figure 70. Root ExtractorThe proposed extractor is based on the use of two operational amplifiers (op amps) as only active elements. Figure 71. Basic Log AmplifierA logarithmic amplifier, or a log amplifier, is an electronic circuit that produces an output that is proportional to the logarithm of the applied input. The simple logarithmic amplifier uses a junction diode as a nonlinear element. In addition, the basic log amplifier can also be constructed by replacing diode by a transistor. The output is proportional to the logarithm of the input given by. Figure 72. Circuit for Operating the LM101 without a Negative Supply Figure 73. Circuit for Generating the Second Positive Voltage Figure 74. Multiple Aperture Window Discriminator Figure 75. Neutralizing Input Capacitance to Optimize Response Time Figure 76. Saturating Serve Preamplifier with Rate FeedbackFrequently Asked Questions about Op Amp Circuits1. What is an op amp circuit?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. Why use an op amp in a circuit?To convert the current into voltage, a simple circuit with an operational amplifier, a feedback loop through a resistor on the non-inverting, and the diode connected between the two input pins allows you to get an output voltage proportional to current generated by the photodiode, which is evident by the light. 3. How do op amp circuits work?An operational amplifier, or op amp, generally comprises a differential-input stage with high input impedance, an intermediate-gain stage, and a push-pull output stage with a low output impedance. ... That is, the output gets fed back to the inverting input through some impedance. 4. What are the advantages of op amps circuit?An op-amp circuit buffers the sensor and allows gain or attenuation circuits to be developed. The output of the sensor is non-linear. An inverting op amp circuit gives you a more linear output than a non-inverting op-amp circuit does. 5. What are the ideal characteristics of op amp?The so-called ideal op amp is to idealize various technical indicators of op amps, and it must have the following characteristics.1) Infinite Input Resistance2) Zero Output Impedance3) Infinite Open-loop Gain4) Infinite Common-mode Rejection Ratio5) Infinite Bandwidth

IntroductionA voltage divider is a passive linear circuit used to create a voltage less than or equal to the input voltage. It is a conversion device composed of a high-voltage arm and a low-voltage arm. The measured high voltage acts on the device, and the output voltage is got from the low voltage arm. The components of the high and low voltage arms are usually resistors and capacitors. The corresponding devices are called resistor dividers, capacitor dividers, and resistance-capacitance voltage divider. Voltage dividers are one of the most fundamental circuits in electronics.What is Voltage Divider? (voltage divider rule)CatalogIntroductionⅠ Overview of Voltage Divider1.1 Voltage Divider Structure1.2 Voltage Divider CircuitⅡ Types of Voltage DividerⅢ Voltage Divider Characteristics3.1 Voltage Divider Basic3.2 Two Major Points in the Voltage Divider Circuit3.3 Common Voltage Divider Features3.4 Voltage Divider FormulaⅣ Voltage Divider RulesⅤ Voltage Divider PotentiometerⅥ Main Differences between Voltage Divider and TransformerⅠ Overview of Voltage Divider1.1 Voltage Divider StructureThe voltage divider is a special instrument for on-site measurement, measuring DC high voltage and AC high voltage. The voltage divider adopts a balanced equipotential shielding structure, and high-quality electronic components are used inside the body. So that it has the characteristics of accurate test, good linearity, stable performance, reasonable structure, easy to carry, simple operation, intuitive display, etc.Figure 1. Voltage Divider Circuit1.2 Voltage Divider CircuitVoltage usually contains two important terms: electromotive force (EMF) and potential difference (PD). When something provides a voltage, such as a battery, it provides the force required to pull electrons along the circuit because of emf. When a component consumes the voltage in the circuit, the amount of voltage drop on it called potential difference. Some rules about voltage can help circuit design, including:1) Series voltages accumulate.2) The parallel voltage is always the same.3) The PD in the component is proportional to its resistance.4) Polarity is decisive.5) Sum EMF around the circuit is equal to the sum of PD.The rule that voltages in series always accumulate affects both EMF and PD. If the batteries are connected in series, their voltages will add up. If there are series-connected components, then you can apply this rule, whose combined PD is the output voltage. Although it is easy to identify potential differences, make sure to pay close attention to the polarity of the power source. Because the battery reverses minus the combined voltage.Figure 2. An Example of a Series of Voltages Added Up Parallel voltages are always the same. It is one of the reasons why it is not a good idea to connect batteries in parallel with different voltages. For example, when two batteries with different voltages are connected in parallel, the battery with the larger voltage will try to charge the smaller battery, which may damage it.Figure 3. An Example of Parallel Voltage Circuit We have known that the series voltages add up and the voltages in parallel are the same. There are also some questions. How does the voltage separate between the elements in the series circuit? What determines the voltage of each component? The voltage division (called potential difference) is determined by the ratio of the resistance of the element to the resistance of the series circuit. This is directly related to the voltage rule:The value of the PD on the component is proportional to its resistance.Basically, this means that the greater the resistance of the component (compared to the series circuit), the greater its potential difference. In fact, the voltage on the component is equal to When considering the classic divider circuit, the formula is usually written as The following is a typical voltage divider circuit with approximately 3.3V from a 5V power supply:(This circuit can be used to connect a 5V output device to the 3.3V input on the microcontroller, such as particle photon.)Figure 4. An Example of a Classic Voltage Divider Circuit When a voltage (EMF) is applied to the circuit, the sum of all potential differences on the series elements will equal the EMF. For example, the voltage provided by the battery will be divided among the components connected in series, and the sum of all these divided voltages will be equal to the voltage of the battery.Figure 5. Series Voltage Circuit Ⅱ Types of Voltage Divider1. According to the applicationa) For laboratoryb) For power system2. According to the measured voltagea) AC voltage dividerThere are two types: resistive type and capacitive type. The resistive type is composed of non-inductive resistance elements suitable for measuring AC voltages with low frequency. The capacitive type is composed of capacitive elements. It basically does not consume power and can be used for higher voltage measurement. The measurement voltage ranges from thousands of volts to millions of volts. So it has a wide rang applications.b) Impulse voltage dividerImpulse voltage is a non-periodic pulse voltage with fast changes and many harmonic components. To accurately measure its waveform and amplitude, the impulse divider is required to have good response characteristics. There are three types: resistive, capacitive, and resistance-capacitance.c) DC voltage dividerIt is composed of two (groups) resistance elements, and a high-impedance voltmeter is usually used to measure the voltage on the low-voltage arm.Figure 6. High-voltage Divider3. According to the principle of voltage dividera) Capacitor dividerThe capacitor divider used to measure the pulse voltage can be divided into two types. One’s high-voltage arm of a voltage divider is composed of multiple high-voltage capacitors stacked, and the high-voltage arm of the other voltage divider has only one capacitor.The former voltage divider is mostly assembled with an oil-paper-insulated pulse capacitor with an insulating shell, which requires that the inductance of this capacitor is relatively small and can withstand short circuit discharge. A high-voltage oil-paper capacitor is assembled by multiple components in series and parallel. Each component not only has capacitance, but also has inherent inductance and contact resistance in series, as well as parallel insulation resistance. Of course, each component has stray capacitance to ground. This kind of voltage divider should be regarded as a distributed parameter, so it is called a distributed capacitor divider.The distributed capacitor divider is formed by stacking multiple pulse capacitors, with only amplitude error and no waveform error. As for the amplitude error, it can be completely eliminated after calibration with a standard voltage divider. However, when measuring steep waves, since the capacitance of the capacitor divider is much larger than the stray capacitance of the shielding ring of voltage divider, the response time is also much longer. So in terms of measuring steep waves, the response characteristics of the capacitor voltage divider are not as good as the shielded resistor divider. The single-capacitor divider does not consume energy and has no trouble of heating. For measuring waves with a longer wavefront and half-peak time, a capacitor divider is better than a resistor divider. In addition, the capacitor divider can also be used as a load capacitor for adjusting the waveform.The high-voltage arm of the centralized capacitor divider can use a standard capacitor charged with compressed gas. The capacitance value of this capacitor is very accurate and stable, and the dielectric loss is small. Because it is shielded, the capacitance value is not affected by surrounding objects. In power frequency measurement, it has been used very commonly. However, when it is used as an impact capacitor voltage divider, some problems will occur. That is, superimposed high-frequency oscillation.b) Resistor dividerIts internal resistance is pure resistance, with characteristics of simple structure, easy to use, good stability, etc. The error generated by it when measuring the transient pulse voltage is related to the product of the resistance value and the stray capacitance to the ground, so the size and impact of the stray capacitance to the ground should be minimized, and the resistor divider should reduce inductance.c) Resistance-capacitance dividerThe resistance-capacitance voltage divider can be divided into a series-type voltage divider and a parallel-type voltage divider according to the connection mode.The resistor-capacitor series voltage divider is also called the damping capacitor voltage divider. Recently, the high-voltage divider belongs to this type. It overcomes the residual inductance of the capacitor circuit and prevents the voltage divider from oscillating, and has excellent performance. According to the difference of the added damping, the RC series voltage divider can be divided into two types: high damping divider and low damping divider. The high damping capacitor voltage divider cannot be used as the load (wave modulation) capacitor of the impulse voltage generator. It is only used as a conversion device for measuring voltage. The series damping resistance of the low damping capacitor voltage divider is very small, and its connection will not make it difficult to generate standard waves in the test circuit. It can also be used as a load capacitor and is a general voltage divider. From the point of view of ease of use, it has more advantages than the high damping capacitor voltage divider. From the response characteristics, it is not as good as the high damping capacitor voltage divider because it also contains oscillation.Theoretically speaking, when the voltage changes rapidly, the voltage divider ratio is mainly determined by the capacitance; when the change is slow, it is determined by the resistance. The device resistance wire is tightly wound on the porcelain tube positively and negatively, and connected in parallel with each capacitor. Practice has proved that the selected resistance value cannot be too small, otherwise it will affect the output load of the generator, so it is generally selected to be relatively large. However, the effect is small. It is similar to a pure capacitive voltage divider without resistance.Figure 7. Voltage Divider CurrentⅢ Voltage Divider Characteristics3.1 Voltage Divider Basic1) The voltage divider adopts high-precision resistor and capacitor assembly, special process potting, and dry seal, so there is no oil leakage problem. 2) High input impedance: the test current is reduced, the power consumption is small, the product is small and light, the performance is stable, and the measurement accuracy is high. 3) The voltage divider, multi-value kilovolt meter and special cables are all placed in an aluminum alloy box, which is safe and reliable, easy to carry and transport. 4) The multi-value kilovolt meter can directly read the DC average value, AC peak value, effective value, peak value and other voltage values.5)The organic composite insulating jacket is used above 150KV, which increases the surface creeping distance, and greatly reduces the height of the product. So the device is more convenient to use and carry.3.2 Two Major Points in the Voltage Divider Circuit1) Input terminalIt is necessary to analyze where the input signal voltage is input to the voltage divider circuit, and what is the specific input current loop. The method of determining the current loop in circuit analysis is as follows: Start from the input end of the signal voltage, follow at least two components (not necessarily resistors) to the ground.2) Output terminalThe signal voltage output by the voltage divider circuit must be sent to the next level circuit. Theoretically, the input of the next level circuit is the output terminal. However, sometimes it is difficult to analyze the input end of the next-level circuit. So you can use a simpler method to analyze: find all the components in the voltage divider circuit, analyze from the ground line to the upper end, and then find a certain component connects with other circuits. This connection point is the output terminal of the voltage divider circuit, and is also the output voltage of the voltage divider circuit.In the process of analyzing the voltage divider circuit, it is often necessary to figure out the size of the output voltage.The calculation method of the output voltage: Uo=R2/R1+R2·Uiwhere Ui is the input voltage, Uo is the output voltage.The output voltage is less than the input voltage, because the voltage divider circuit attenuates the input signal voltage. That is, changing the size of Rl or R2 resistance can change the output voltage Uo.3.3 Common Voltage Divider FeaturesResistor Divider(1) When it is wound by constantan wire with a small temperature coefficient or kama wire with a small temperature coefficient and high resistance, its temperature stability is high, and the long-term stability is also high during operation. (2) Using a compressive resistor divider structure, its response characteristics may be relatively high.Capacitor Divider(1) The distributed capacitor divider is formed by stacking multiple pulse capacitors, with only amplitude error and no waveform error.(2) The high-voltage arm of the centralized capacitor divider can use a standard capacitor filled with compressed gas. The capacitance value of this capacitor is very accurate and stable, and the dielectric loss is small. Because it is shielded, the capacitance value is not affected by surroundings.Resistance-capacitance DividerThe high damping capacitor voltage divider cannot be used as the load (wave modulation) capacitor of the impulse voltage generator. It is only used as a conversion device for measuring voltage. The series damping resistance of the low damping capacitor voltage divider is very small, and its access will not make it difficult to generate standard waves in the test circuit. It can also be used as a load capacitor, which is a general voltage divider.3.4 Voltage Divider FormulaHow do you calculate voltage divider? In a series circuit, the voltage distribution is proportional to the size of the resistance, that is, the larger the resistance is, the greater the voltage is distributed; on the contrary, the smaller the resistance is, the smaller the voltage is distributed. Voltage divider produces an output voltage (Vout) that is a fraction of its input voltage (Vin).In a series circuit, the voltage across the conductors is proportional to their resistance.By I1=I2, U1/R1=U2/R2 is Using Apogee’s Voltage Divider Calculator helps determine the output voltage of the divider circuit given the input (or source) voltage and the resistor values. Simply enter a few values, and this tool will show the illustrated results for you immediately. Ⅳ Voltage Divider RulesWhen use and test voltage divider, you should take care of the following rules:1) There should be no debris on the test site, so as not to affect the measurement accuracy.2) The ground wire must be connected firmly to ensure a safe operating distance.3) After the test, it must be fully discharged.4) It is strictly prohibited to use over-rated voltage.5) Ensure that the surface of the equipment is clean and stored in a cool, dry place. Ⅴ Voltage Divider PotentiometerThe potentiometer is a varistor that can be used to create an adjustable voltage divider. Its  absolute resistance value will not affect the output voltage, and the output voltage is proportional to the input voltage. Commonly used potentiometers have poor resistance accuracy and temperature coefficient. However, as long as the resistance of the potentiometer is uniform, the voltage will be divided evenly. Assuming that the slider is connected to a high-impedance circuit, the contact resistance of the slider will not affect the output voltage. The sliding sheet contact resistance is a value at the contact point of the sliding sheet.When the potentiometer acts as a variable resistor, its resistance accuracy and temperature coefficient will affect the circuit. The contact resistance of the slide will affect the resistance of the circuit, and the contact resistance of the slide will change with changes in position, temperature, vibration and time. Ⅵ Main Differences between Voltage Divider and Transformer1) The transformer changes the ac voltage of by causing the induced electromotive force through the change of the magnetic flux. The capacitor divider changes the alternating voltage through the capacitive reactance during the charging and discharging process.2) The transformer can step up or step down; the capacitor divider cannot step up.3) The input power of the ideal transformer changes with the change of the output power; while the input power of the voltage divider does not change when there is no load.4) When an ideal transformer works, the magnetic flux passing through the iron core is constant. The voltage across the coil follows Faraday's law of electromagnetic induction, in addition, when the voltage divider works, its loop current is a constant value. Frequently Asked Questions about Voltage Divider Rule and Formula1. What is voltage divider rule formula?Using the voltage divider ratio rule, we can see that the largest resistor produces the largest I*R voltage drop. Thus, R1 = 4V and R2 = 8V. Applying Kirchhoff's Voltage Law shows that the sum of the voltage drops around the resistive circuit is exactly equal to the supply voltage, as 4V + 8V = 12V. 2. What is the purpose of a voltage divider?A voltage divider can be used to scale down a very high voltage so that it can be measured by a volt meter. The high voltage is applied across the divider, and the divider output—which outputs a lower voltage that is within the meter's input range—is measured by the meter. 3. What is the voltage divider equation?Voltage Divider Formula / EquationR2 / R1 + R2 = Ratio determines scale factor of scaled down voltage. For example, Vin = 100, R1= 20, R2= 10. 4. What is a voltage divider rule?In electronics, the voltage divider rule is a simple and most important electronic circuit, which is used to change a large voltage into a small voltage. ... When the i/p voltage is applied across the pair of the resistor and the o/p voltage will appear from the connection between them. 5. How does a voltage divider work?A voltage divider can be used to scale down a very high voltage so that it can be measured by a volt meter. The high voltage is applied across the divider, and the divider output—which outputs a lower voltage that is within the meter's input range—is measured by the meter.

IntroductionIn electronics, a comparator is an electronic circuit that compares two voltages (or currents) and outputs a digital signal indicating which is larger. Comparing two or more data to determine the number size and arrangement order between them. In addition, it is a circuit that compares an analog voltage signal with a reference voltage. The two inputs of the comparator are analog signals, and the output is a binary signal 0 or 1, and the output is ideally. When the difference of the input voltage changes and the positive and negative sign remains constant, the output remains unchanged. Comparators play an essential role in designing electrical and electronic projects.What is A Comparator?CatalogIntroductionⅠ Working PrincipleⅡ Main Parameters2.1 Hysteresis Voltage2.2 Bias Current2.3 Super Power Swing2.4 Drain-source Voltage2.5 Output Delay TimeⅢ Comparator Classification3.1 Voltage Comparator3.2 Window Comparator3.3 Hysteresis ComparatorⅣ Comparator ICsⅤ How Do You Select a Comparator?Ⅵ Comparator Applications6.1 Zero-crossing Comparator 6.2 Relaxation Oscillator (ROSC)6.3 A/D Converter6.4 Voltage ComparatorⅦ Op Amp ComparatorⅠ Working PrincipleGenerally, in electronics, the comparator is used to compare two voltages or currents which are given at the two inputs of the comparator. A comparator circuit compares two voltages and outputs either a 1 (the voltage at the plus side; VDD in the illustration) or a 0 (the voltage at the negative side) to indicate which is larger. The operational amplifier can be used as a comparator theoretically without negative feedback. However, the open-loop gain of the operational amplifier is very high, so it can only process signals with a very small input differential voltage. Moreover, in general, the delay time of the op amp is long, which cannot meet the actual requirements. The comparator can be adjusted to provide a very small time delay, but its frequency response characteristics will be limited. To avoid output oscillation, many comparators also have internal hysteresis circuits. The threshold of the comparator is fixed, some have only one threshold, and some have two thresholds.Comparator SymbolⅡ Main Parameters2.1 Hysteresis VoltageThe voltage between the two input terminals of the comparator will change the output state when it crosses zero. Because the input terminal is often superimposed with a small voltage fluctuation, the differential mode voltage generated by it will cause the comparator output to change frequently.  In order to avoid output oscillation, the new comparator usually has a hysteresis voltage of several mV. The existence of it requires two switching points of the comparator: one is used to detect the rising voltage, the other is used to detect the falling voltage. The difference of the voltage threshold (VTRIP) is equal to the voltage hysteresis (VHYST). The offset voltage of hysteresis comparator is the average of TRIP and VTRIP-. The input voltage switching point of the comparator without hysteresis is the input offset voltage, not the zero of the ideal comparator. In addition, the offset voltage generally varies with temperature and power supply voltage. And the power supply rejection ratio is usually employed to express the influence of power supply voltage changes on the offset voltage.2.2 Bias CurrentThe input impedance of an ideal comparator is infinite. Therefore, there is no effect on the input signal theoretically. However, the actual input impedance of the comparator cannot be infinite. There is a current at the input end that flows through the internal resistance of the signal source and flows into the comparator, thereby generating an additional voltage difference. The bias current (Ibias) is defined as the median of the input currents of the two comparators and is used to measure the effect of input impedance.2.3 Super Power SwingTo further optimize the operating voltage range of the comparator, Maxim uses the parallel structure of the NPN tube and the PNP tube as the input stage of the comparator. Thus the input voltage of the comparator can be expanded. In this case, the lower limit can be lower to the lowest level, and the upper limit is 250mV higher than the power supply voltage to reach the Beyond-the-Rail standard. The input of this comparator allows a larger common-mode voltage.2.4 Drain-source VoltageThe comparator has only two different output states (zero level or power supply voltage). Its output stage of the comparator with full power swing characteristics is an emitter follower, which makes its voltage difference smaller between input and output signals. The voltage difference depends on the emitter junction voltage under the saturation state of the internal transistor of the comparator, which is equal to the drain-source voltage of the MOSFFET.2.5 Output Delay TimeIt includes the transmission delay of the signal through the components and the rise time and fall time of the signal. For high-speed comparators, such as MAX961, the typical value of the delay time can reach 4.5ns and the rise time is 2.3ns. Pay attention to the influence of different factors on the delay time when designing, including the influence of temperature, capacitive load, input overdrive and so on.Although the comparator has different types. The design and construction of each should take care of ordinary uses without affecting its measuring accuracy. The instrument should be very sensitive and withstand a reasonable ill usage without permanent harm.Ⅲ Comparator ClassificationComparators are classified into various kinds, such as electronic, electrical, mechanical, optical, sigma, digital and pneumatic comparators. These are used in various applications. Here we are talking about electronic comparator.3.1 Voltage ComparatorA voltage comparator is a circuit that discriminates and compares input signals, and is a basic unit that forms a non-sine wave generating circuit. Voltage comparators are commonly used including single-limit comparators, hysteresis comparators, window comparators, and three-state voltage comparators. Voltage comparator can be used as an interface between analog circuits and digital circuits, as well as waveform generation and conversion circuits.3.2 Window ComparatorCombine two comparators to form a "window comparator", which is widely used. The window comparator can set the upper limit voltage and lower limit voltage of the input at the same time, within limited voltage range, or outside the range, which we need. When the potential level of the high-level signal is higher than a certain specified value VH, it is equivalent to the positive saturation output of the comparator circuit. When the potential level of the low-level signal is lower than a certain specified value VL, it is equivalent to the negative saturation output of the comparator circuit. The comparator has two thresholds, and the transmission characteristic curve is window-shaped, so it is called a window comparator.3.3 Hysteresis ComparatorIt is a comparator with hysteresis loop transmission characteristics, and can be understood as a single-limit comparator with positive feedback. When the input voltage vI gradually increases from zero and VI is less than VT, the comparator output is a positive saturation voltage, and VT is called the upper threshold (trigger) level. When the input voltage VI>VT, the comparator output is a negative saturation voltage, and VT is called the lower threshold (trigger) level.Ⅳ Comparator ICsCommon chips are LM324, LM358, uA741, TL081234, OP07, OP27, which can all be made into voltage comparators (without negative feedback). LM339 and LM393 are professional voltage comparators with fast switching speed and small delay time, which can be used in special voltage comparison occasions. Ⅴ How Do You Select a Comparator?The working principle of a comparator is simple and straightforward. It has a positive pin and a negative pin. When the voltage on the positive pin is high, the output drives a signal. When using open-collector output, the output pin of the comparator is the collector of a transistor or the drain of a FET. When using push-pull output, the comparator has a complementary NPN/PNP stage, like in an operational amplifier. The open-collector output is used when the load and the comparator use different power supplies. This kind of scheme can realize the solenoid of 12V, although the comparator may only work at 3.3V. Another function of the open-collector output is to minimize the quiescent current when the output is turned off. Among them, no base current flows in the N-type output transistor, and some base current always flows through one of the two output transistors.However, open-collector output also has some disadvantages. For example, they require external pull-up resistors. These resistors must complete the pull-up task during the high-impedance period, so that when the output is lower than turn-off, the comparator can switch faster, and the pull-up resistor makes the output high. Therefore, when you need a symmetrical waveform, it is not suitable to use an open collector output, such as a clock recovery circuit. If your circuit does not require level conversion, you should choose push-pull output, such as ALD2321APC, it can provide 24mA output drive capacity, quiescent current is 90μA.The high-speed comparator may also have a latched output, so that the output can be kept in a known state to meet the set-up and hold time requirements of the digital input behind it. Once the digital part has read the output of the comparator, the latch pin can be released and the output can track the input.High-speed comparators may also use ECL (emitter coupled logic) levels from -5V to 0V. PECL (positive emitter coupled logic) outputs have the same voltage swing, from 0V to 5V. There is also RSPECL (reduced amplitude PECL) output. The two output pins of some high-speed comparators use LVDS (low-voltage differential signaling) output, which converts 300mV around a 1.2V common-mode voltage in a complementary manner. You can send these outputs directly to the LVDS input pins of FPGA (field programmable gate array) and other digital circuits.In production, CMOS technology is generally used to build low-power devices, while bipolar devices are used to build high-speed devices. This represents a basic compromise: high-power high-speed, accurate devices, and low-power, low-speed devices. Another compromise is gain and high speed. The low-power comparator may take 70µs conversion time and consume less power. The response time of the high-speed comparator is 150ps. Some devices can overcome the trade-off between speed and power consumption. When converting at the highest rate, the power consumed by the comparator is much higher than its static power consumption. In the static state, the current is low. When the comparator is operated at a higher speed, it must be able to charge the capacitor. In dynamic mode, the current increases as the working speed increases. Another factor in power consumption is the load on the chip. For a switching current, the capacitance will also become a load, and the capacitive and resistive components in the load must be considered. Many devices are related to broken pins, which can reduce the power consumption to less than 1µA.As with all simulation, the declared propagation delay is meaningful only under strictly defined conditions, because the degree to which the input pin is driven directly affects the propagation delay. The greater the overdrive, the faster the device. Dispersion is the range of propagation delay values of a device under various overdrive levels. The relationship between overdrive and speed is one reason why some engineers are reluctant to consider comparator speed as a function of slew rate. It necessary to define the output level that is quantized as a valid transition, usually the maximum output level is 10% to 90%. The slew rate also represents a requirement for overdrive, that is, to keep the propagation delay as short as possible.Another parameter to consider when choosing a comparator is noise. However, manufacturers often omit noise specifications of the comparators and instead use random jitter to measure noise. In addition to the noise signal passing through the device gain, the input aperture error and the output rise and fall time can also affect jitter. A clock-driven device is nothing but a lower gain comparator optimized for noise. Designers can use larger input transistors in a CMOS device to reduce flicker noise, but this method increases the input capacitance.The next consideration should be the rated voltage of the comparator. One factor related to the power supply interval is the allowable common-mode voltage at the input pins of the comparator. Some devices allow you to pull the output to a voltage range higher or lower than the power supply. For other devices, when you pull the input pin below the negative power rail, the output will be inverted. Comparator with rail-to-rail input stage expands the range of input common-mode mode. These devices have a dual-input stage, using N-type transistors or FETs in parallel with the P-type input stage. The input voltage of the P-type input stage operates at near the ground or the negative voltage rail, and the N-type input stage works when the input swings to the positive voltage rail. IC designers generally make the device switch between level 1 or 2V below the positive voltage rail. When sweeping over the rail-to-rail devices, some structures can minimize the offset voltage.Another important specification of the comparator is the input offset current, that is, the amount of current flowing into or out of the input pin when the device is working. CMOS products have a low offset current, which represents a mismatch in the leakage of the input pin ESD (electrostatic discharge) structure. For every 10°C increase in temperature, the input offset current doubles. The offset current of high-speed comparators can be obvious, but it is not a problem because low-impedance circuits are generally used to drive these high-speed comparators. The input offset current of a bipolar device depends on the relationship between the two inputs. In a comparator, a 60mV difference in the base voltage of a differential input pair will get a 10 times higher difference between the pair's collector current and the input offset current. Therefore, one pin can pull or sink twice the rated input offset current, while the other pins have almost no input offset current, depending on which pin has a higher voltage.Ⅵ Comparator Applications6.1 Zero-crossing Comparator The zero-crossing comparator is used to detect whether an input value is zero. The principle is using a comparator to compare two input voltages. One of the two input voltages is the reference voltage Vr and the other is the voltage to be measured Vu. Generally, Vr is connected from the non-inverting input terminal, and Vu is connected from the inverting input terminal. According to the result of comparing the input voltage, the forward or reverse saturation voltage is output. When the reference voltage is known, the measured result of the voltage can be obtained. When the reference voltage is zero, it is a zero-crossing comparator.The zero-crossing comparator has a small measurement error. When the product of the voltage difference between the two input terminals and the open-loop magnification is less than the output threshold, the detector will give a zero value. For example, when the open-loop magnification is 106 and the output threshold is 6v, if the voltage difference between the two input stages is less than 6 microvolts, the detector outputs zero. This can also be considered the uncertainty of measurement.6.2 Relaxation Oscillator (ROSC)Comparators can construct relaxation oscillators by using positive feedback and negative feedback. Positive feedback is a Schmitt trigger, which forms a multivibrator. The RC circuit adds negative feedback to it, which causes the circuit to start to oscillate spontaneously, making the entire circuit from a latch to a relaxation oscillator.Level shifting uses open-drain comparators (such as LM393, TLV3011, and MAX9028) to construct a level shifter to change the signal voltage. Choosing an appropriate pull-up voltage can flexibly get the converted voltage value. For example, use the MAX972 comparator to convert ±5V signals into 3V signals.6.3 A/D ConverterThe function of the comparator is to compare whether an input signal is higher than a given value. So it can convert the input analog signal into a binary digital signal. Almost all digital-to-analog converters (including delta-sigma modulation) contain comparators circuit to quantize the input analog signal.6.4 Voltage ComparatorThe voltage comparator can be regarded as an operational amplifier with an infinite amplification factor. The function of the voltage comparator: compare the magnitude of two voltages (using the high or low level of the output voltage to indicate the magnitude relationship between the two input voltages): When the voltage at the "+" input terminal is higher than the "-" input terminal, the voltage comparator output is high level; when the "+" input terminal voltage is lower than the "-" input terminal, the voltage comparator output is low level.It can be used as an interface between analog circuits and digital circuits, and can also be used as a waveform generation and conversion circuit. A simple voltage comparator can change the sine wave into a square wave or rectangular wave with the same frequency. The simple voltage comparator has a simple structure and high sensitivity, but its anti-interference ability is poor, so people have to improve it. The improved voltage comparators include: hysteresis comparator and window comparator. Operational amplifiers are used to determine "operational parameters" through feedback loops and input loops, such as magnification. The feedback amount can be part or all of the output current or voltage. The comparator does not need feedback and directly compares the quantity of the two input terminals. If the non-inverting input is greater than the inverted phase, the output is high, otherwise it outputs low. The input of the voltage comparator is a linear quantity, and the output is a switch (high and low level). In typical applications, a linear op amp can sometimes be used to form a voltage comparator without negative feedback. Ⅶ Op Amp ComparatorIn principle, operational amplifier can be used as comparator without negative feedback. However, because of its high open-loop gain, it can only process signals with very small input differential voltage. Moreover, in this case, the response time of the operational amplifier is much slower than that of the comparator, and it also lacks some special functions, such as hysteresis, internal reference and so on. Comparator usually can not be used as an operational amplifier. Comparator can provide minimal time delay after adjustment, but its frequency response characteristics are limited to some extent. Operational amplifier makes use of the advantage of frequency response correction to become a flexible and versatile device. In addition, many comparators also have internal hysteresis circuit, which can avoid output oscillation, but it can not be used as an op amp. Frequently Asked Questions about Comparator Electronics1. What is a comparator and its application?A comparator is an electronic component that compares two input voltages. Comparators are closely related to operational amplifiers, but a comparator is designed to operate with positive feedback and with its output saturated at one power rail or the other. 2. How does a comparator circuit work?The comparator circuit work by simply taking two analog input signals, comparing them and then produce the logical output high “1” or low “0“. ... When the analog input on non-inverting is less than the analog input on inverting input, then the comparator output will swing to the logical low. 3. What is the purpose of a comparator in op amp?Op-amp window comparators are a type of voltage comparator circuit which uses two op-amp comparators to produce a two-state output that indicates whether or not the input voltage is within a particular range or window of values by using two reference voltages. An upper reference voltage and a lower reference voltage. 4. How do you use comparator electronics?A comparator circuit compares two voltages and outputs either a 1 (the voltage at the plus side; VDD in the illustration) or a 0 (the voltage at the negative side) to indicate which is larger. Comparators are often used, for example, to check whether an input has reached some predetermined value. 5. What is comparator and its types?Comparators are classified into various kinds, such as electronic, electrical, mechanical, optical, sigma, digital and pneumatic comparators, these are used in various applications. Comparators play an essential role in designing electrical and electronic projects.

IntroductionWhat is a triac? TRIAC (Triode for Alternating Current) is an electronic component that is widely used in alternating current power control. It is a three terminal electronic component that conducts current in either direction when triggered. TRIAC is able to switch high voltages and high levels of current, and over both parts of an AC waveform. This makes triac circuits ideal for use in a variety of applications where power switching is needed. You can find its applications in switching, phase control, chopper designs, brilliance control in lamps, speed control in fans, motors etc.TRIAC Characteristics, TRIAC Structure and TRIAC WorkingCatalogIntroductionⅠ TRIAC vs Silicon Controlled Rectifiers (SCR)Ⅱ TRIAC Structure and SymbolⅢ How Do You Use a TRIACⅣ How Does a TRIAC Work?4.1 TRIAC Leakage Current4.2 SolutionsⅠ TRIAC vs Silicon Controlled Rectifiers (SCR)Thyristor also called SCR stands for silicon controlled rectifier while TRIAC stands for triode for alternating current. The TRIAC has on and off state characteristics similar to SCR. The main difference between SCR and TRIAC is that thyristor is a unidirectional device while in TRIAC as a bidirectional device. A TRIAC is defined as a three terminal AC switch which is different from the other silicon controlled rectifiers (SCR) in the sense. They can turn and regulate both parts of the AC waveform easily. This makes this component appropriate for a variety of applications where control of AC power is needed. A dimmer circuit will be an example application, and we use it domestically as a ceiling fan regulator circuit. Also it can be used to regulate a motor or electric heater's input power. This is why TRIAC is used for applications of low to medium power, leaving SCR with high-power applications. While this is a very interesting system, a problem known as "leakage current" is present. And we'll talk more about this leakage current, its adverse effects, and some well-known ways to solve these problems in this article. But let's clear out the basics of TRIAC before that. Ⅱ TRIAC Structure and SymbolAs for triac symbol, like any other electronic component, it consists of two SCRs linked in an antiparallel configuration, and if we look very closely at its symbol, it clearly reflects the TRIAC's bidirectional properties. Which you observe from the picture below.The upgraded variant of the thyristor is the TRIAC. A thyristor can only control current in one direction, as you already know, but a TRIAC can control current in both negative and positive directions. TRIAC turns in each sine wave loop because of the existence of the sine wave, which means we can use the entire cycle, unlike SCRs. Like thyristor, a TRIAC has three terminals, but it becomes a little difficult to assign names to these terminals since they are related simply to the cathode and the anode of two SCRs. Two SCRs are also connected to the gate terminal, which is why it was called Anode 1 and Anode 2 or Main Terminal 1 and Main Terminal 2 (MT1 and MT2).A multimeter can be used to test the health of a triac. First put the multimeter selector switch in a high resistance mode (100K), then connect the positive lead of multimeter to the MT1 terminal of triac and negative lead to the MT2 terminal of triac (there is no problem if you reverse the connection). Ⅲ How Do You Use a TRIACTriacs are semiconductor devices that are widely used for switching medium power AC. Let's acquire a little knowledge of  TRIAC functions before going further. As the following figure shows you.Two-thyristor AnalogyWe have previously said that as a configuration of two SCRs, a TRIAC can be realized. The above image provides a little bit more clarity on the subject, but it is much more complex to work at the semiconductor level. A TRIAC can be activated in many ways, unlike SCR, regardless of the polarity of the terminals. Regardless of the polarity of the initiating pulse, it may also be activated. When working with TRIAC, one thing to remember is that when the MT2 and gate current are at the same polarity, the sensitivity of the trigger current is much greater. We can now move on to cleaning out our key issue of leakage current with the simple cleared out.Triac Switching Circuit ExampleⅣ How Does a TRIAC Work?4.1 TRIAC Leakage CurrentThere is structural leakage current in the off state of thyristor, TRIAC, or any other solid-state AC switches, which is why a small amount of current flows through the load, this circuit is sufficient in some cases to charge a load circuit (Inductive) and causes it to flash spontaneously. We need to take careful care of the specifics and design the circuit accordingly to avoid this, and we will talk more about it in this section of this article.If the voltage of MT2 reaches a certain rated threshold voltage (which can occur due to the transient state of high voltage), the leakage current between the two terminals may enter the point at which the TRIAC breaks into conduction mode. In this state, a sudden localized heat will be produced when a sudden increase in current flows through the TRIAC, so that the TRIAC can be destroyed. Incandescent lamps are most likely the source of strong inrush currents, with capacitive loads.4.2 SolutionsBy applying one or more of the following methods, this condition can be avoided:1) Maximum Temperature Ratings Tj max. ensure that the temperature is not surpassed. As temperature rises, the current of leakage through the system increases, we can eliminate/reduce this issue by integrating specific TRIAC brands for specific requirements.2) By placing a broad value resistor from the gate to the cathode, we can reduce the TRIAC's sensitivity. This decreases the gate current, thereby reducing the current of leakage. It, on the other hand, increases the TRIAC turn-on time.3) If it is not possible to implement the methods described above, we can use a TRIAC with a less sensitive gate during the off time and apply a small degree of reverse bias to the gate. In this process, we have to minimize the dissipation of power through the gate.4) Depending on the form of load, another strategy for reducing leakage current is to fully eliminate the snubber circuit. The capacitor leakage also becomes the main source of leakage current, so we can decrease the current flow through the snubber and decrease the leakage current by removing the snubber network.If you want to know more TRIAC info, you can check its Triac I-V Characteristics curves with more examples. Before try these methods to reduce current leakage, please remember safety first! Frequently Asked Questions about TRIAC Basic and Its Applications1. What is a triac used for?The Triac is most commonly used semiconductor device for switching and power control of AC systems as the triac can be switched “ON” by either a positive or negative Gate pulse, regardless of the polarity of the AC supply at that time. 2. Which is an example of Triac?TRIAC ApplicationsTRIAC is very commonly used in places where AC power has to be controlled for example, it is used in the speed regulators of ceiling fans, AC bulb dimmer circuits etc. Let us look into a simple TRIAC switching circuit to understand how it works practically. 3. What is triac and its characteristics?A Triac is defined as a three terminal AC switch which is different from the other silicon controlled rectifiers in the sense that it can conduct in both the directions that is whether the applied gate signal is positive or negative, it will conduct. Thus, this device can be used for AC systems as a switch. 4. What is a triac switch?A Triac is a high-speed solid-state device that can switch and control AC power in both directions of a sinusoidal waveform. Being a solid state device, thyristors can be used to control lamps, motors, or heaters etc. 5. What is the working principle of Triac?The triac is another three-terminal ac switch that is triggered into conduction when a low-energy signal is applied to its gate terminal. Unlike the SCR, the triac conducts in either direction when turned on.