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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, transient voltage suppressor (TVS) diodes are components that protect sensitive circuitry from being damaged due to high voltage transients. Because tvs diodes are constructed with large cross sectional area junctions for absorbing high transient currents. The primary source of high voltage transients are electrostatic discharge, electrical fast transient, and surge events. This notes will tell you how does a tvs diode work to prevent a circuit malfunction and protect devices.CatalogIntroductionⅠ Transient Voltage Suppressors (TVS)1.1 What Transient Means??1.2 What Causes a Circuit to Be Transient?1.3 What Does a TVS Do?1.4 What Can Be A Transient Voltage Suppressor?Ⅱ Transient Voltage Suppression Diode2.1 TVS Diode Overview2.2 How To Choose A TVS Diode?Ⅲ How Do You Use TVS Diode for Circuit Protection3.1 TVS Diode in Circuits3.2 Major TVS Diode ParametersⅣ ConclusionⅠ Transient Voltage Suppressors (TVS)1.1 What Transient Means?Transients are spikes of short duration in voltage or current that can in several ways damage a circuit. Some transients only occur once, and some of them may be repetitive. These transients vary from a few millivolts to thousands of volts and can last for hundreds of milliseconds to nanoseconds. Due to inductive load switching or defective contacts in switches and connectors, transients may be produced internally. It can be produced externally because of lightning strikes or inductive switching.1.2 What Causes Transient Voltage?Transient voltages are caused by the sudden release of stored energy due to incidents such as lightning strikes, unfiltered electrical equipment, contact bounce, arcing, capacitor bank or generators being switched ON and OFF. Transient voltages differ from swells by being larger in magnitude and shorter in duration. Transient voltages typically last from less than a microsecond to several milliseconds. Transient voltages are generally classified into two different types depending on where they occur on a power system: normal mode or common mode.1.3 What Does a TVS Do?Transient voltage suppressors or TVS are devices of protection used to save the circuits from this unexpected voltage or current spike. Positioning these TVS devices in parallel with the circuit is the primary way to protect a circuit from overvoltage.1.4 What Can Be A Transient Voltage Suppressor?Metal oxide varistor, TVS diode, Zener diode or bypass capacitor are several types of TVS devices that can be used for transient voltage suppression diodes.Transient Voltage Suppressors can be divided into two types, clamping and crowbar. Clamping devices restrict the voltage to a level which is fixed. They consume the excess energy of the overvoltage event in doing so. An instance of clamping devices is TVS diodes.On the other hand, once activated, Crowbar devices effectively shorten the protected line, redirecting the excess energy away from the protected circuit. As you can see in the graph below, when a trigger voltage (spike) is detected, the crowbar device shorts the circuits such that the line voltage is decreased, then the line voltage rises again to a stable state for regular circuit operation after some time as the crowbar device delays the circuit.Transient Voltage Suppression Diode SymbolⅡ Transient Voltage Suppression Diode2.1 TVS Diode OverviewThe transient voltage suppression diode ((ESD protection diode)) is a solid-state PN-Junction diode explicitly designed to remove the sudden or momentary effects of overvoltage on sensitive semiconductors and circuits. TVS diode is a clamping system, so it absorbs the excess energy of the overvoltage event if the induced voltage reaches the avalanche breakdown voltage, and then automatically resets after overvoltage situation. Although it is true that standard diodes and Zener diodes can also be used for overvoltage/transient safety, since standard and Zener diodes are designed for rectification and voltage control, they are not as robust as transient voltage suppressor diodes.How Does Transient Voltage Suppressor Diode Work?2.2 How To Choose A TVS Diode?When selecting a suitable transient suppressor, it is necessary what types tvs diode have? Like every other avalanche diode, a unidirectional transient voltage suppressor diode acts in the forward direction as a rectifier in a circuit, and this unidirectional diode is made to withstand very high peak currents. The unidirectional TVS diode symbol is seen in the picture below, and it's almost like a Zener diode.On the other hand, two mutually opposing avalanche diodes connected in series with each other can represent a bidirectional transient-voltage-suppression diode. In parallel with the system or circuit to be secured, these diodes are connected. These diodes are produced as a single element, unlike the symbol. The Bidirectional TVS Diode symbol is shown in the picture below.Introduction to Transient Voltage Suppressors (TVS) CharacteristicBefore take a tvs diode in circuit, it is critical to specify the peak impulse capability for a given transient waveform. In most diodes, the peak pulse capability will be rated either 8/20µs or 10/1000µs impulse waveform. It is possible to classify Transient Voltage Suppressor Diodes into two groups. One of them is unidirectional, and the other is bidirectional.Ⅲ How Do You Use TVS Diode for Circuit Protection3.1 TVS Diode in CircuitsIn parallel with the system or circuit to be secured, TVS diodes are attached. The TVS system is specifically designed to break down at a particular voltage level and, without sustaining damage, conduct large quantities of current.The TVS diode appears as an open circuit under normal voltage conditions, but a low leakage current is present. The TVS diode junction avalanches when the usual voltage reaches a certain amount and overvoltage is redirected from the safe circuit as a result and shunted through the TVS diode. When the overvoltage goes down, the system automatically resets.In addition, the VI characteristic curve of the tvs diode is similar to that of a Zener diode, TVS diodes are specifically designed, characterized, and tested for transient voltage suppression. By contrast, zener diodes are designed and specified for voltage regulation.3.2 Major TVS Diode ParametersMany types of TVS diodes, equipped for a particular application, are on the market. When selecting a TVS diode to protect an external interface, there are a couple of key parameters you want to pay special attention to. Here is the following parameters in the datasheet to help you find a right TVS diode.Reverse Stand-Off Voltage (VR)The highest voltage that can be applied to the protector without the system actually being triggered is the reverse stand-off voltage. The VR of the system should be equal to, or greater than, the peak operating voltage of the safe circuit. This is to ensure that the regular circuit operation or signal voltage is not clipped by the safety system.Breakdown voltage (VBR)The voltage at which the diode can begin to protect and conduct current is the breakdown voltage. The VBR is usually defined at 1mA.Clamping Voltage (VC)The clamping voltage is the maximum voltage that will be exposed to the safe circuit during the event of the test waveform. The clamping voltage for a 1A or 2A waveform that has an 8μS rise time is given on most datasheets.Peak Pulse Current (IPP)The highest current which the safety system can withstand is the peak pulse current.Ⅳ ConclusionThe TVS diode is commonly used in low-energy circuits and systems for diversion/clamping, and in circuits for ESD safety. Because one advantage of using external TVS diodes is that they typically provide level four IEC ESD protection. Under normal operating conditions, the TVS diode presents a high impedance to the protected circuit. Ideally, the device appears as an open circuit, although a small amout of leakage current is present. TVS diode applications can be found in data and signal lines, memory for microprocessors and MOS, power lines for AC/DC, and telecommunication equipment. Frequently Asked Questions about TVS Diodes1. What is Transient-voltage-suppression diode?A transient-voltage-suppression (TVS) diode, also transil or thyrector, is an electronic component used to protect electronics from voltage spikes. In other words, transient voltage suppressor diodes are very popular devices used to instantaneously clamp transient voltages (e.g., ESD events) to safe levels. 2. How does a transient voltage suppressor diode work?Transient Voltage Suppressor Diode is a clamping device, so whenever the induced voltage exceeds the avalanche breakdown voltage, it absorbs the excess energy of the overvoltage event, and then it automatically resets after overvoltage condition. 3. What does a transient voltage suppressor do?Transient Voltage Suppressors (TVS) are devices used to protect vulnerable circuits from electrical overstress such as that caused by electrostatic discharge, inductive load switching and induced lightning. 4. What does a suppression diode do?A transient-voltage-suppression (TVS) diode, also transil or thyrector, is an electronic component used to protect electronics from voltage spikes induced on connected wires.

Ⅰ IntroductionMost Integrated ICs need a constant voltage that they can work with. They have their own operating voltage, whether it's a basic Logic Gate or a sophisticated microprocessor. 3.3V, 5V and 12V are the most common operational voltages. Although we have batteries and DC adaptors that can serve as a source of voltage, because the voltage from them is not controlled, they can not be directly linked to our circuit design most of the time.Say, we have a 9V battery, for instance, but we need to activate a 5V relay, which obviously works on 5V. What are we doing here?CatalogⅠ IntroductionⅡ Definition and Using of Voltage Regulator Ⅲ A Closer Look at Voltage RegulatorsⅣ Three Terminal RegulatorsⅤ Voltage Regulators: Increase the Output CurrentⅥ Adjustable RegulatorsⅦ Limitations of Voltage RegulatorⅧ FAQⅡ Definition and Using of Voltage Regulator You recall your school days when we were told that voltage drops from resistors. Wouldn't it be an easy fix to only use resistors according to Ohms Law to lower the voltage? But then, depending on the current flowing through them, resistors decrease voltage. The moment your part begins to draw less current, it shoots up and destroys the voltage.You need something better; the voltage, at least not much, does not depend on the load current. The voltage divider is the next easiest repair that comes to your head. This involves two resistors, but hey, they can also operate if they can be crammed in. Another nagging problem-the moment your part begins to draw so much current, the divider sags output-the top resistor can not keep up with the current demand. Now you're really starting to wish you had heard about this in school. By reducing the resistor values, you might resolve this, but that would make the two resistors draw too much current, likely to destroy your current budget and get too hot with the immediate risk of failure. What could be done else? Amplifying! You had, of course, to slog through hours of lectures on that. As a voltage follower, why not add an NPN transistor? The bias of the voltage divider could be connected to the foundation, the rail input of 12V to the collector and the output to the emitter part, and bingo, you solved the problem. The repair works, of course, but it leaves you with a nagging feeling-you've used three pieces, and you find out on checking that bugs are perfectly repeated on the performance in the 12V supply rail. This is an amplifier, of course, and it doesn't have the intellect to compensate for itself. You can replace the voltage divider's bottom resistor with a Zener diode, but the current needed to correctly bias a Zener (against things such as temperature coefficients and drift) is almost as much as your part consumes, which is pointless. Isn't there an easier way for this to happen? Isn't there a magic black box containing anything needed to effectively drop the voltage? Similar cycles of stress (including me) have influenced millions of EEEs around the world. Of course, not all issues are correlated with falling voltages, but EEE labs are popular in similar situations everywhere! But you're in luck—there is the exact part you need. In fact, the humble voltage regulator is one of the earliest commercial implementations of the IC technology (apart from op-amps).If you ever look at a voltage regulator's datasheet, you'll be amazed at the circuitry with which they have been packed to drop a voltage and keep it clean-a nice stable voltage regulator, feedback and compensation amplifiers, and a half-good power level. Of course, if we were able to cram so much technology into our own phones, why not make a nice TO-92 kit with some voltage control? Some of them consume no more than a few nanoamps, which is a thousandth of a millionth of an amp! They keep getting stronger every day. Even better, some come with protection against short circuits and overtemperature, rendering them foolproof.Ⅲ A Closer Look at Voltage RegulatorsThe primary role of a voltage regulator, as we have seen in the section above, is to drop a larger voltage to a smaller one and keep it steady, as the regulated voltage is used to power (sensitive) electronics. As mentioned above, a voltage regulator is essentially a beefed-up emitter follower-a transistor linked to a stable reference that spits out a constant voltage, dropping the remainder. They also have an error amplifier built-in, which samples the output voltage (through a divider again), compares it to the reference voltage, calculates the difference, and drives the output transistor accordingly. This is far from a voltage divider, which replicates the input signal faithfully, but at a smaller magnitude. You don't want to see your DC voltage rail overlaid with an AC ripple.A transistor with a high gain is ideal, because power transistors are a massive pain to drive, with pathetic gains in the two-digit range. By using Darlington transistors and, more recently, MOSFETs, this has been solved. As these types require less power to drive, there is a decrease in overall current consumption. This is balanced by the fact that very little current is often absorbed by the voltage reference used internally. The current absorbed by the regulator to drive all this internal circuitry is called the quiescent current when the output is not loaded. The lower the current of silence, the stronger. There are three transistors on the power output level, two of them in a Darlington configuration and the other as a current limiting unit, the way these regulators are designed. The successive CE junctions add up to a voltage drop across the regulator of about 2V. This voltage is known as the voltage dropout, the voltage at which the regulator ceases controlling.With a voltage drop of about 0.4V, you can find devices called LDOs or low dropout regulators, because they use a MOSFET switch.Ⅳ Three Terminal RegulatorsEnough speaking, now for the actual numbers of the pieces. The 78XX series is the most common series of voltage regulators. For example, the 7805 is a 5V regulator and the 7812 is a 12V regulator. The two digits after the 78 reflect the output voltage of the regulator. A wide range from 3.3V to 24V covers the output voltages available with fixed regulators with pleasant values such as 5V, 6V, 9V, 15V and 18V available. For most purposes, this series of regulators are outstanding, they can handle up to almost 30V at the input and up to 1A output current depending on the kit. Attach the input pin to the input voltage and the output pin to the unit that requires the lower voltage and, of course, the ground pin to ground. They are exceptionally easy to use. Since the feedback amplifiers 'reject' input ripple and noise, ensuring that they do not move on to the output, decoupling capacitors are optional here. However, if more than a few tens of milliamps are drawn by your unit, at least 4.7uF on the input and output is recommended, preferably in ceramic. Using these regulators, an odd thing people do is make rudimentary phone chargers. Only add a 9V battery to the input and a suitable USB connector to the output, and you've got an emergency phone charger for yourself. Thanks to the built-in thermal safety on the chip, this design is very robust. A positive thing about these kinds of voltage regulators is that the pinouts are almost interchangeable, so it is possible to plug-in replacements. Most of the 'transistor' packages on PCBs nowadays are voltage regulators that can be picked up because they are so easy to use for other projects.Ⅴ Voltage Regulators: Increase the Output CurrentThe performance current, which is heavily restricted by the package and the way the package is installed, is one limitation that easily overcomes the utility.These regulators have high-current versions, but they are difficult to identify.DC-DC switching converters are the only machines capable of spitting out high currents, but the performance noise figures are awful.It is possible to build your own high current linear regulator, but inevitably you will run into all the above-mentioned issues.Luckily, with a few extra bits, there is a way to 'hijack' a normal regulator and increase the product currently.Most of these modifications include inserting a bypass transistor across the regulator and, as shown in the figure below, driving the base with the input. Ⅵ Adjustable RegulatorsIt's very pleasant and simple to use three-terminal regulators, but what if you want a non-standard output voltage like 10.5V or 13V?Of course, fixed regulators can be hijacked more or less, but the necessary circuitry is very complex and beats the primary objective of simplicity.Devices exist that can do the job for us, with the LM317 being the most common.The LM317 is just like every other linear regulator with an input and an output pin, except there's a pin named 'adjust' instead of a ground pin. This pin is intended to receive input through the output from a voltage divider such that the pin is always at 1.25V, we can obtain various voltages by changing the resistance values. The datasheet also states,' removes several fixed voltages being held,' but this only applies, of course, if you can afford to have those two resistors on board. A good thing about adjustable regulators like this is that they can also act as continuous current supplies with a minor configuration change.The regulator aims to maintain a constant 1.25V throughout the output resistor and thus a constant current on the output by attaching a resistor to the output pin and the adjustment pin to the other end of the resistor as shown in the figure. For the diode laser group, this simple circuit is very common.This can also be achieved by fixed regulators, but the dropout voltages are unreasonably high (in fact, the rated output voltage). However, they can work in a pinch if you're desperate. Ⅶ Limitations of Voltage RegulatorThe greatest benefit of linear regulators is their simplicity; it is not important to say anything else. However, they come with their own set of limitations, like all good chips. Linear regulators work with feedback like a variable resistor, falling any unneeded voltage. The same current as the load is drawn when drawing. This wasted energy is converted to heat, rendering these regulators at high currents warm and inefficient. A 5V regulator with a 12V input that runs at 1A, for example, has a power loss of (12V-5V)*1A, which is 7W! That's a lot of wasted energy and that's just 58 percent production! So, regulators have pathetic energy efficiency at high input-output voltage differentials or high currents. Using more than one regulator in a series of decreasing output voltages (up to the desired voltage value), the input-output differential voltage problem can be solved so that the voltage is lowered in steps. Although the total dissipation of power is the same as having one regulator, the heat load is distributed through all devices, reducing the overall operating temperature. By using a switching supply, the power and efficiency constraints can be resolved, but the option is application-dependent, there are no straight cut rules as to when to use which type of power supply. Ⅷ FAQ1. What is Dropout Voltage or headroom in Voltage regulators?A linear regulator such as the famed 7805 outputs 5.0 volts. The dropout specification is going to be about 2 Volts typical, 2.5 maximum. That means it will regulate 5 V as long as the input unregulated voltage is above 2 to 2.5 V above the regulated output voltage of 5 V. That gives it a 2 volt (7 minus 5) headroom. The headroom is considered to be the minimum input-output differential it can maintain. if the input falls to 6.5 volts the regulator outpupt can be expected to be about 4.5 volts. It means, counting diode drops, and ripple amplitude, you must keep above the dropout voltage or you will see the ripple in your output. 2. How does a voltage regulator work?It works on the principle of detection of errors. The output voltage of an AC generator obtained through a potential transformer and then it is rectified, filtered and compared with a reference. The difference between the actual voltage and the reference voltage is known as the error voltage. This error voltage is amplified by an amplifier and then supplied to the main exciter or pilot exciter. Thus, the amplified error signals control the excitation of the main or pilot exciter through a buck or a boost action (i.e. controls the fluctuation of the voltage). Exciter output control leads to the controls of the main alternator terminal voltage. 3. Can a voltage regulator convert AC to DC?Depends on the topology and the circuit components that are used.A circuit that converts AC to DC is called a rectifier. Additional circuits like buck-boost converters can be used to regulate the DC.In a generic sense, most voltage regulators are marketed for AC systems. They are back-to-back converters which rectify AC to DC and then invert DC to AC after suitable modification to the wave shape. It is possible to take the intermediate DC output after the rectification stage and suitably modify it with further circuitry. 4. What are the 2 types of voltage regulators?Two types of regulators are used: step regulators, in which switches regulate the current supply, and induction regulators, in which an induction motor supplies a secondary, continually adjusted voltage to even out current variations in the feeder line. 5. How do you use a voltage regulator?The first 0.33uF capacitor shorts any AC noise on the line to the ground and cleans the signal up for the input of our regulator. The regulator in this circuit is a TS7805CZ (5V 1A) regulator, which then steps the 12V voltage signal down to 5V, and pushes this on the output. 6. What is the difference between voltage stabilizer and voltage regulator?Basically, no major differences. A stabilizer has only a limited input voltage range and is mostly used for low power devices and the regulator has a higher range of input voltages, for medium and high power devices. Both ensure a regulated, constant output voltage. Stabilizers are a type of voltage regulator. 7. 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. 8. What causes voltage regulator failure?There are different reasons why the regulator rectifier fails. ... Ground connections are important for good voltage, and if there is faulty voltage, the regulator rectifier can run hot. Bad grounding, corroded battery connection and poor or loose battery connections will cause faulty voltage. 9. What is the purpose of an automatic voltage regulator?An automatic voltage regulator (AVR) is an electronic device that maintains a constant voltage level to electrical equipment on the same load. The AVR regulates voltage variations to deliver a constant, reliable power supply. 10. How long does a voltage regulator last?For the most part, the instrument voltage regulator is supposed to last for the life of the car. Like with any other electrical component of a car, eventually, this voltage regulator will begin to show signs of damage. 

Executive Summary: 2026 MOV GuideWhat is an MOV? A Metal Oxide Varistor (MOV) is the industry-standard component used to protect electronic circuits from high-voltage surges and transient spikes.Key Function: It acts as a voltage-dependent switch—normally maintaining high resistance, but switching to low resistance within nanoseconds during a spike to shunt destructive energy away from sensitive components.2026 Standard: Modern circuit design mandates sizing MOVs based on Clamping Voltage, Peak Pulse Current, and Energy Rating (Joules) to ensure compliance with IEC and UL safety standards.What Is the Role of MOVs in Circuit Protection?The role of an MOV in circuit protection is to act as the critical first line of defense against destructive voltage transients by shunting excess electrical energy away from sensitive components. The blue or orange circular component typically found on the AC input side of a power supply circuit is a Metal Oxide Varistor, or MOV. As of 2026, the MOV remains indispensable in modern electronics, supporting a global surge protection device market projected to exceed $4.5 billion. It functions as a specialized variable resistor that automatically adjusts its resistance based on voltage levels. Under normal conditions, it does nothing; however, when high current or voltage spikes occur, the MOV instantaneously decreases its resistance to function as a short circuit. To fully protect circuits from catastrophic failure, MOVs are almost exclusively used in combination with a fuse. In this updated guide, we will explore the engineering principles behind MOVs, their electrical characteristics, and how to select the precise component for robust 2026 circuit designs.What Is a Metal Oxide Varistor (MOV)?A Metal Oxide Varistor (MOV) is a bidirectional, non-linear surge protection component that shunts excessive current to the ground during a voltage spike. Unlike manual potentiometers, MOVs adjust their resistance automatically and nearly instantaneously (typically in under 25 nanoseconds). As the voltage across the device increases, its resistance decreases drastically. This inverse relationship is the core mechanism that shields sensitive microcontrollers and power ICs from mains surges. A standard radial lead MOV used in consumer electronics is depicted below.Protection ComponentEnergy HandlingResponse TimePrimary ApplicationMOV (Metal Oxide Varistor)High (Joules)< 25 nsAC Mains & Power SuppliesTVS DiodeLow to Medium< 1 nsDC Data Lines & MicroprocessorsGDT (Gas Discharge Tube)Very High> 1 µs (Slow)Telecommunications & Heavy IndustrialHow Does a MOV Work?An MOV works by maintaining a high-resistance state during normal voltages and rapidly switching to a low-resistance state when a voltage spike exceeds its clamping threshold. Under normal operating voltage, the MOV maintains extremely high resistance (Mega-ohms), drawing negligible current and acting as an open circuit. However, when a transient spike exceeds the specific "clamping voltage" (or knee voltage), the MOV's semiconductor structure undergoes an avalanche breakdown. It rapidly switches to a low-resistance state, drawing the surge current and dissipating the excess energy as heat, thereby clamping the voltage to a safe level for downstream equipment. Critical Limitation: MOVs are designed to handle short-duration transients (microseconds), not sustained over-voltage conditions. Repeated exposure to high-energy surges degrades the internal zinc oxide structure. Over time, the clamping voltage drifts lower, eventually leading to thermal runaway or failure. To mitigate this risk in 2026 standard designs, MOVs are often placed in series with a thermal cutoff (TCO) or fuse that disconnects the circuit if the MOV overheats.How Are MOVs Integrated into Electrical Circuits?MOVs are universally connected in parallel to the circuit they protect, usually situated immediately after the safety fuse but before the transformer or rectifier. The diagram below illustrates the standard topology for AC mains protection. Operational Flow:Normal State: Voltage is within rated limits. The MOV has high resistance. Current flows to the load; no current flows through the MOV.Surge Event: A lightning strike or grid switching causes a voltage spike. The voltage appears directly across the parallel MOV.Clamping Action: The high voltage forces the MOV into a conductive state (low resistance). It effectively shorts the lines. This "short circuit" action draws a massive surge of current. If the surge is significant, this current rush blows the safety fuse, physically isolating the circuit from the mains. While the MOV sacrifices itself (and often the fuse) during catastrophic events, it saves the expensive components (logic boards, motors) downstream. If you find a burnt MOV in a power supply, it indicates it successfully did its job by absorbing a lethal voltage spike.What Materials Are Used to Construct an MOV?The Metal Oxide Varistor is a sintered ceramic component composed primarily of Zinc Oxide (ZnO) grains (approximately 90%), doped with other metal oxides such as cobalt, manganese, and bismuth. These ceramic powders are sandwiched between two metal plates (electrodes) and encapsulated in an epoxy resin. Microscopic Function: The grain boundaries between zinc oxide crystals act as miniature P-N junction diodes. Essentially, a single MOV functions as millions of back-to-back Zener diodes connected in series and parallel. At low voltage, the reverse leakage current is minimal. When high voltage is applied, electron tunneling and avalanche breakdown occur at these grain boundaries, allowing massive current flow.MOVs are manufactured in various form factors including radial discs (most common), axial leads, and high-energy blocks. For heavy industrial applications requiring massive power handling, multiple MOVs are connected in parallel. Conversely, they are connected in series to achieve higher voltage ratings.What Are the Key Electrical Characteristics of an MOV?To interpret a datasheet in 2026, engineers must understand the specific behavior of MOVs under static and dynamic conditions, specifically focusing on static resistance, the V-I clamping curve, and parasitic capacitance.A. Static ResistanceThe resistance of an MOV is not fixed. The graph below plots Resistance (Y-axis) against Voltage (X-axis).As shown, resistance is highest at the rated operating voltage. As voltage climbs toward the clamping threshold, resistance plummets logarithmically, allowing current conduction. B. V-I Characteristics (The Clamping Curve)Unlike a linear resistor (Ohm's Law), the MOV follows a non-linear VI curve, similar to two back-to-back Zener diodes.Leakage Region (0V to ~200V): High resistance. Current is in micro-amperes ($mu$A).Conducting Region (200V to 250V): As voltage enters the breakdown region, current rises to milli-amperes.Clamping Region (>250V): The device becomes highly conductive. Current jumps to Amperes, clamping the voltage to protect the circuit. C. Parasitic CapacitanceBecause an MOV consists of two electrodes separated by a dielectric, it acts as a capacitor. This parasitic capacitance (ranging from pF to nF) is negligible for DC or mains frequency (50/60Hz) power circuits. However, for high-frequency data lines, this capacitance can attenuate signals. Reactance is calculated as $X_c = 1 / (2pi f C)$. Engineers must select low-capacitance varistors for high-speed data protection.How to Select the Right MOV (2026 Selection Guide)Selecting the correct MOV requires matching the device specifications to your circuit's voltage and surge requirements. Use the following parameters as your checklist:Maximum Continuous Operating Voltage (MCOV): The highest RMS or DC voltage the device can withstand continuously without conducting. Rule of Thumb: Select an MCOV 10-20% higher than your actual line voltage (e.g., use a 150V or 275V rated MOV for 120V/240V lines respectively).Clamping Voltage ($V_c$): The voltage level where the MOV "locks" or clamps during a surge. This must be lower than the maximum withstand voltage of the components you are protecting.Surge Current Rating ($I_{max}$): The maximum peak current the MOV can handle for a specific pulse duration (usually 8/20 $mu$s). Higher is always better for longevity.Energy Absorption (Joules): The maximum energy the MOV can dissipate in a single event. A higher Joule rating means the MOV can absorb larger or longer transients without failing.Response Time: Modern MOVs respond in nanoseconds (typically < 25ns), which is sufficient for lightning and switching surges.Degradation Factor: Every surge absorbed slightly degrades the MOV's V-I curve. In 2026 designs, over-specifying the Energy and Current ratings extends the lifespan of the protection circuit.Where Are MOVs Commonly Used?MOVs are commonly used in AC power strips, switch-mode power supplies, and telecommunications equipment to suppress transient voltage spikes. They are versatile and found in nearly all power electronic devices.Key Applications:Power Strips & Surge Protectors: The most common consumer application.Power Supplies (SMPS): Connected across AC mains (Line-Neutral) to stop grid spikes.Motor Control: Protecting MOSFETs and Thyristors from back-EMF and switching arcs.Telecommunications: Protecting lines from lightning induction (often using low-capacitance variants).Consumer Electronics: Laptops, LED drivers, and chargers.How Do You Design a Robust MOV Protection Circuit?To design a robust protection circuit, engineers must strategically balance voltage margins, energy ratings, and fail-safe mechanisms. Here are professional design tips for integrating MOVs into 2026-era electronics: 1. Voltage Margin Strategy: Never match the MOV voltage rating exactly to the line voltage. For a 230V AC line, a 275V AC rated MOV is standard practice. This buffer prevents the MOV from conducting during minor, harmless voltage fluctuations, which would overheat the device over time. 2. Energy Calculation: Estimate the worst-case surge energy. If your environment is prone to heavy industrial switching or lightning, prioritize the **Joule rating**. A physically larger MOV (disk diameter) generally handles more energy. 3. The "Fail-Safe" Requirement: When an MOV fails, it often fails as a short circuit. If not fused properly, this can cause a fire. ALWAYS place a fuse upstream of the MOV. Modern designs often use a "Thermally Protected MOV" (TMOV) which contains an integrated thermal fuse that opens if the MOV overheats due to sustained overvoltage. 4. Parallel Configuration: For extremely high reliability, engineers place multiple MOVs in parallel to split the surge current, though this requires matched VI characteristics to ensure even current sharing.Frequently Asked QuestionsWhat is the difference between an MOV and a TVS diode?A Metal Oxide Varistor (MOV) handles massive energy surges (Joules) and high currents, making it ideal for AC mains protection. In contrast, a Transient Voltage Suppressor (TVS) diode responds faster and clamps at precise voltages, making it better suited for protecting low-voltage DC data lines and sensitive microprocessors.How do you test if a Metal Oxide Varistor is blown?To test an MOV, disconnect power and use a digital multimeter set to resistance (Ohms). A healthy MOV should read as an open circuit with infinite resistance. If the multimeter reads zero or very low resistance, the MOV has shorted internally and must be replaced immediately to restore protection.Can an electrical circuit work without an MOV?Yes, a circuit will function normally without an MOV because the device operates in parallel and draws no current under standard conditions. However, operating without one leaves the circuit completely vulnerable to voltage spikes, meaning a single power surge could instantly destroy the downstream components.Why does an MOV blow the fuse during a surge?An MOV is designed to drop its resistance to near zero during a high-voltage spike, creating a deliberate short circuit. This sudden short draws a massive influx of current from the mains, which intentionally overloads and blows the upstream fuse, physically disconnecting the circuit from the dangerous power source.{"@context": "https://schema.org","@graph":[{"@type": "Article","headline": "Metal Oxide Varistor (MOV): The 2026 Guide to Circuit Protection","description": "A comprehensive guide to Metal Oxide Varistors (MOVs). 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IntroductionOver voltage protection is necessary to prevent damage as a result of electrical transients. It is a power supply feature which shuts down the supply, or clamps the output, when the voltage exceeds a preset level. Most power supplies use an over-voltage protection circuit to prevent damage to the electronic components. They offer some form of overvoltage-protect (OVP) circuit to detect and then quickly pull down the overvoltage. When the voltage exceed the rated maximum breakdown voltage, do you know using Zener diode to make overvoltage protection circuit? Here introduces the Zener diode overvoltage protection circuit, which is the most common way.CatalogIntroductionⅠ Over Voltage BackgroundⅡ Zener Diode Input Protection BasicsⅢ Simple Overvoltage Protection Circuit Using Zener DiodeⅣ How Do You Choose a Zener Diode to Protect a Circuit?Ⅴ Zener Overvoltage Protection OverviewⅠ Over Voltage BackgroundEvery circuit design operates at various voltage levels, with 3.3V, 5V, and 12V being the most common voltage levels for a digital circuit. But every design is special, and having more than one operating voltage is also normal for a circuit. For example, a standard computer SMPS system will work at six different levels of voltage, namely ±3.3V, ±5V, and ±12V. In these cases, if a low-power device is operated by a high voltage, the component will be permanently impaired if various voltage levels are used to power different types of components. Therefore, to avoid over-voltage harm, the designer should always concentrate on implementing an over-voltage security circuit in his designs.There will be three different voltage ratings for any part or circuit, namely the minimum operating voltage, the suggested or normal operating voltage and the maximum operating voltage. For any circuits or parts, any value over the maximum operating voltage can be fatal. Using a Zener diode over voltage protection circuit is a very common and cost-effective solution. Ⅱ Zener Diode Input Protection BasicsIn order to protect the circuit from overvoltage conditions, Zener diodes are often the first option. A Zener diode follows the same diode theory, which blocks the current flow in the reverse direction. However, there is a drawback that the Zener diode blocks the flow of current in the reverse direction only for a restricted voltage defined by the voltage rating of the Zener diode. A 5.1V Zener diode blocks current to flow in the opposite direction up to 5.1V If the voltage is greater than 5.1V through the Zener diode, it allows the current to pass through it. This Zener diode function makes it an excellent over-voltage security component.Over-Voltage Protection Circuit using Zener DiodesⅢ Simple Overvoltage Protection Circuit Using Zener DiodeConsider a circuit, where need microcontroller over-voltage protection. Anything that has a maximum rating of 5V across the microcontroller IO pins. So voltage more than 5V will damage the microcontroller.Figure 1. Overvoltage Protection for MicrocontrollerThe diode used in the circuit above is a Zener diode of 5.1V. During an over-voltage case, it will work perfectly. It can transfer the current and regulate the voltage up to 5.1V if the voltage is more than 5.1V. In practice, however, it will behave as a regular diode and block less than 5.1V The image below is a simulation of the spice circuit of Zener diode protection. For the full simulation description, you can make it based on your need.Figure 2. Simulating Overvoltage Protection CircuitThere is an input voltage in the schematic above, which is dc supply. The R1 and D1 are two components that protect the output from protection from over-voltage. The D1, 1N4099, in this case, is a Zener diode. When the V1 reaches 6.8V, the output will be protected. The output would remain at a maximum of 6.8V as a reference voltage of 1N4099.Let's see how the above circuit works as the protection circuit of the Zener diode input and protects the output from more than 6.8V voltage.Using pspice cadence, the above circuit is simulated. The output remains constant at 5.99V at the 6V input voltage across the V1 (Which is 6.0V).The input voltage in the above simulation is 6.8V. The performance, therefore, is 6.78V, which is similar to 6.8V. Let's further raise the input voltage and create a situation of overvoltage.Now, 7.5V, which is more than 6.8V, is the input voltage. The performance is now now at 6.88V. This is how a Zener diode is successful in saving the connected circuit from a situation of overvoltage, even when the voltage returns to less than 6.8V, as shown in the previous stage, the circuit will operate normally again. In other words, a Zener diode does not get fried even during an overvoltage state, unlike a fuse.To pick different overvoltage margins in the above circuit, any other Zener diodes with different values such as 3.3V, 5.1V, 9.1V, 10.2V can be used. Ⅳ How Do You Choose a Zener Diode to Protect a Circuit?The next critical part is choosing the value of the Zener Diode. The points below will assist you in selecting the correct Zener Diode value and part number.1) Choose the voltage of the Zener diode first. It is the voltage value that will serve as a close circuit for the Zener diode and protect the load from overvoltage. The Zener voltage is 6.8V in Pspice, for the above example.There will be some cases where there is no usable targeted Zener diode voltage. In such instances, it is possible to choose a near value of the Zener diode. For example, for overvoltage security up to 7V, a near value is a 6.8V Zener diode.2) Calculate the load current that is linked across the circuit of overvoltage safety. This is 50mA for our example discussed above. Other than the load current, biasing current is required by Zener diodes. Therefore, the total current, plus the Zener diode biasing current, should be equal to the load current. For the above mentioned example, it can be total current=50mA+10mA=60mA.3) There is a power ranking for Zener diodes. Therefore, for proper heat dissipation, the correct Zener diode power rating is required. Based on the measured total current in Phase - 2, which is 60mA, the power rating can be calculated. Therefore, the power rating of the Zener diode would be equal to the voltage of the Zener diode, which connects the total current flowing through the diode.4) Calculate the value of the resistor by differentiating the voltage of the source and the general voltage. The limit which can be applied to the circuit would be the source voltage. For example, it can be 13V to maximize overvoltage that can occur or can be added as a supply voltage.The voltage drop through the resistor will then be = 13V-6.8V = 6.2V According to the law of the ohm, the resistor value will be = 6.2V / 0.060 A = 103R It is possible to choose the standard value 100R resistor.5) Zener diode typical values are 5.1V, 5.6V, 6.2V, 12V and 15V -most common; they are also have 3V, 5V, 12V, 18V, 24V.Ⅴ Zener Overvoltage Protection OverviewZener diode as a voltage regulator, it is suitable for overvoltage protection circuit. Because the easiest and simplest process to protect devices from overvoltage is overvoltage-protect circuit using Zener diodes. The voltage remains regulated in this technique and the cost of this circuit is much lower compared to other techniques.Although, surely, there are disadvantages to this sort of circuit. Power dissipation is the main downside of this type of circuit. It still dissipates heat due to the linked series resistor and results in energy wastage. Frequently Asked Questions about Zener Diode Overvoltage Protection Circuit Design1. What is overvoltage protection?Over voltage protection is a power supply feature which shuts down the supply, or clamps the output, when the voltage exceeds a preset level. Most power supplies use an over-voltage protection circuit to prevent damage to the electronic components. 2. Which is most common circuit protection device?The SPD(surge protection device) device is allied in parallel in the power supply circuit, which can be used on all stages of the power supply system. The surge protection device is the most frequently used and also well-organized kind of over-voltage protective devices. 3. What can cause overvoltage?The main causes include insulation failure, arcing ground and resonance etc. 4. How does a Zener diode regulate voltage?Zener diodes are widely used as voltage references and as shunt regulators to regulate the voltage across small circuits. When connected in parallel with a variable voltage source so that it is reverse biased, a Zener diode conducts when the voltage reaches the diode's reverse breakdown voltage.