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BMP180 is an atmospheric pressure sensor.The BMP180 sensor is mainly used to measure atmospheric pressure or biometric pressure. The working principle of the air pressure sensor is very simple, it works based on the weight of air. Because the air around us has a certain weight, and this weight has a specific pressure.This blog provides you with a basic overview of the BMP180 Sensor, including its pin descriptions, functions and specifications, equivalent products, etc., to help you quickly understand what BMP180 is.We will be glad to find that this blog can be useful for people lovingelectronic components :)This video shows how to use the BMP180 digital temperature and pressure sensor with ArduinoCatalogBMP180 Sensor PinoutBMP180 Sensor FeaturesBMP180 Sensor SpecificationsBMP180 Sensor EquivalentsWhere to Use BMP180 SensorHow to Use BMP180 SensorBMP180 Sensor ApplicationBMP180 Sensor PackageComponent DatasheetFAQBMP180 Sensor PinoutBMP180 is available in two different modules. One is the Five Pin module, the other is the Four Pin module. With the Five Pin module, we have an additional +3.3V pin, which is missing in the four pin module. Apart from the fact that the operation is the same.Pin NameDescriptionVCCConnected to +5VGNDConnected to ground.SDASerial Data pin (I2C interface)SCLSerial Clock pin (I2C interface)3.3VIf +5V is not present. Can power module by connecting +3.3V to this pin.BMP180 Sensor FeaturesCan measure temperature and altitude.Pressure range: 300 to 1100hPaHigh relative accuracy of ±0.12hPaCan work on low voltages3.4Mhz I2C interfaceLow power consumption (3uA)Pressure conversion time: 5msecPotable sizeBMP180 Sensor SpecificationsOperating voltage of BMP180: 1.3V – 3.6VInput voltage of BMP180MODULE: 3.3V to 5.5VPeak current: 1000uAConsumes 0.1uA standbyMaximum voltage at SDA, SCL : VCC + 0.3VOperating temperature: -40ºC to +80ºCBMP180 Sensor EquivalentsBMP280, BMP085, etcWhere to Use BMP180 SensorThere are many reasons why BMP180 is preferred over other modules.Case 1: Where you want to have accurate atmospheric pressure. In many of the modules on the market, BMP180 measures barometric pressure more precisely.Case 2: Where there is a question of power consumption. The BMP180 MODULE consumes much less power to function. This module can be used on battery-operated systems such as smart watches and mobile phones.Case 3: where high-speed communication is needed. BMP180 MODULE capable of communicating with a high-speed TWI interface.The use of the BMP180 module is further promoted with altitude measurement, high speed sensor and temperature sensor on board than other modules.How to Use BMP180 SensorAs seen in PIN DIAGRAM, there are only two pins available to communicate with the module. And that communication is the I2C interface. The data is sent to the module or received from the I2C interface module. So we've got to get information about barometric pressure and temperature through this interface. A typical BMP180 circuit diagram with ARDUINO is shown below.As shown in the circuit diagram, the module is connected to the +5V power supply or the ARDUINO UNO Vout pin. The module can operate on +5V regulated power and a higher voltage can damage the module. The I2C interface is defined as shown in the figure. All you need to do is connect the module SDA PIN to the ARDUINO SDA PIN and the module SCL PIN to the ARDUINO SCL.Although connecting to the BMP180 sensor module is easy to communicate with, it is not easy. The exchange of data between the ARDUINO controller and the module is really complex. Usually to send information to the module, or to receive information from it, we have to follow the protocol. This protocol is a sequence of steps that must be followed without error. These steps are complex for starters to follow. So it's ideal to use libraries that are pre-written for the module. The use of libraries makes communication easier. All you need to do is download and call these libraries in programs. Once the header file is included, the ARDUINO automatically follows the protocol and decodes the required data. Once this data is available, we can perform the desired functions.We can therefore use the BMP180 module easily by using the libraries.BMP180 Sensor ApplicationIndoor navigationSport devicesComputer PeripheralsGPSWeather forecastVertical velocity IndicationHobby projectsBMP180 Sensor PackageMeasurements in millimeterThat’s all for our introduction to BMP180. If you find this blog useful, please bookmark our website Apogeeweb, we will provide you with electronic component blogs, industry news, tools, etc. that you are interested in. Stay tuned for our next blog...Component DatasheetBMP180 DatasheetFAQWhat is BMP180?The BMP180 is the new digital barometric pressure sensor of Bosch Sensortec, with a very high performance, which enables applications in advanced mobile devices, such as smart phones, tablet PCs and sports devices.What Does Barometric Pressure Sensor Do?The barometric sensor, also commonly known as the barometric air pressure sensor (BAP), is a type of engine management sensor commonly found on many vehicles. It is responsible for measuring the atmospheric pressure of the environment that the vehicle is driving in. ... The BAP is similar to the engine MAP sensor.How Do I Connect My BMP180 to Arduino?Connections are fairly simple. Start by connecting VIN pin to the 5V output on the Arduino and connect GND to ground. Now we are remaining with the pins that are used for I2C communication. Note that each Arduino Board has different I2C pins which should be connected accordingly.How Do You Check a Barometric Pressure Sensor?The BARO sensor can be checked with a scan tool by comparing the scan tool read out to the local barometric reading. Standalone Ford sensors require a special tool to determine if the sensor is functioning properly. The ECM will set DTC P0105 when there is an open or short in the BARO circuit. 

I. DescriptionTDA2030A is one of the high-fidelity integrated power amplifiers, and many power amplifier circuits use this integration method. TDA2030 is also a HI-FI power amplifier integrated block used by many computer active speakers. It has simple connection method and affordable price. The rated power is 14W. The power supply voltage is ±6～±18V. The output current is large, the harmonic distortion and the crossover distortion are small (±14V/4 ohm, THD=0.5%). It has excellent short circuit and overheat protection circuit. The following describes its connection and application circuit.CatalogI. DescriptionII. Connection2.1 Single Power Connection2.2 Dual Power ConnectionIII. Application Circuit3.1 OTL Form Power Amplifier3.2 OCL Form Power Amplifier3.3 BTL Form Power Amplifier3.4 40W Power Amplifier Circuit3.5 High-fidelity Active Speaker Circuit3.6 25W Bridge Low Frequency Power Amplifier CircuitIV FAQOrdering & QuantityII. ConnectionIts connection method is divided into single power supply and dual power supply:2.1 Single Power ConnectionFigure 1 TDA2030 single power connection diagram2.2 Dual Power Connection Figure 2 TDA2030 dual power connection diagramIII. Application Circuit 3.1 OTL Form Power AmplifierOTL form power amplifier: single power supply, output coupling capacitor. The R5 (150 kΩ) and R4 (4.7 kΩ) resistors in the circuit shown in Figure 3 determine the closed-loop gain of the amplifier. The smaller the R4 resistor, the greater the gain, but too large gain can easily cause signal distortion.Two diodes are connected between the power supply and the output terminal to prevent the inductive load of the speaker from kicking back and affecting the sound quality. The capacitor of C3 (0.22 uF) and the resistance of R6 (1 Ω) are used to compensate the inductive load (speaker) to eliminate self-excitation. The circuit uses a 36V single power supply and the output power is about 20W.Figure 3 OTL type power amplifier made with TDA2030A3.2  OCL Form Power AmplifierThe form of the OCL power amplifier adopts dual power supplies and has no output coupling capacitor. As shown in Figure 4, since the low frequency response of the output coupling capacitor is improved, it is a high-fidelity circuit. The dual power supply uses a transformer with the middle point of the primary coil grounded and the upper and lower voltages are symmetrical and equal. After rectification and filtering, a ±18 V dual power supply is formed, and the output power is 20W.Figure 4 OCL type power amplifier made with TDA20303.3. BTL Form Power Amplifier The main feature of BTL is: it is composed of two identical power amplifiers, and the input signals are inverse to each other. The in-phase input and the inverted input of the amplifier are actually used to ensure that the input signals are inverse to each other. At the same time, the amplitudes of the two input signals should be the same, so that the basic requirements of the BTL circuit form can be met.The circuit diagram is shown in Figure 5, where R7 (1 kΩ) and R8 (33 Ω) resistors divide the signal and the attenuation factor is exactly the same as the amplification factor of U1. The attenuated signal is added to the inverting input terminal of U2 through R5 .In fact, two op amps complete a signal amplification, and the actual measured output level is 1.5 times higher than that of an integrated circuit. That is, the original output power of the op amp is 20 W, and the output power is now about 50 W.However, due to the characteristics of the BTL circuit, when choosing an integrated circuit, use two operational amplifier circuits with the same parameters as much as possible to adjust the input signal amplitude. You can use an oscilloscope to observe the amplitude of the two input signals by inputting a sine wave. At this time, adjust R7 to make the two input signals The amplitude is the same to ensure that the nonlinear symmetry distortion is minimized while increasing the power.Figure 5 BTL type power amplifier made with TDA2030A3.4 40W Power Amplifier Circuit Figure 6 is a 40W power amplifier circuit made by TDA2030 power amplifier integrated block and BD907/908:Figure 6 40W power amplifier circuit made by TDA20303.5 High-fidelity Active Speaker Circuit A high-fidelity active speaker circuit designed with TDA2030, the circuit diagram is shown in Figure 7. Using dual power supply, added high and low bass and volume adjustment. When designing the PCB, the ground wire should not pass through the component pins as much as possible to reduce DC noise.Figure 7 High fidelity active speaker circuit diagram3.6 25W Bridge Low Frequency Power Amplifier CircuitFigure 8 25W bridge low frequency power amplifier circuitThe circuit in Figure 8 uses two TDA2030s connected to form a bridge circuit, with the same circuit structure and parameters on both sides. The integrated circuit on the right is controlled by the integrated circuit on the left through a 22kΩ negative feedback resistor, and vice versa. The diode 1N4001 is used to prevent the speaker inductive load from generating overvoltage and damaging the device. The amplification factor of the circuit can be adjusted by changing the negative feedback voltage ratio between the output terminal (pin 4) and the inverting input terminal (pin 2).IV FAQWhat is the rated power of TDA2030A?14W What type of circuit does TDA2030 have?Short circuit and overheat protection circuit Can I replace TDA2030 with tda2050?Can i replace tda2030 with tda2050 ? This is the most commonly asked question about these two ic. The answer is yes because the pin configurations of tda2030 and tda2050 are the same. Which IC subwoofer is best?Subwoofer Amplifier Circuit using IC TDA2030. If we want to design the amplifier circuit, the audio amplifier circuit using the IC TDA2030 is the best choice. Because this IC is inexpensive, very simple to utilize, and apt for electronic beginners. Is Class D amplifier better?Class A design is the least efficient but has the highest sound fidelity. Class B design is a little more efficient, but full of distortion. Class AB design offers power efficiency and good sound. Class D design has the highest efficiency but isn't quite as high-fidelity. 

How to check if TL431 is broken? If TL431 is really broken, then how to replace it? These two kinds of problems will be discussed in this blog.How to TEST TL431 Voltage Reference / TL431A TL432 KIA431 Shunt Regulator CircuitCatalogI Introduction1.1 What is TL431?1.2 TL431 PinoutII How to Measure TL431?III How to Test TL431?IV TL431 Replaceable ModelsV ConclusionComponent DatasheetFAQI Introduction1.1 What is TL431?TL431 is a 2.5～36V Adjustable Shunt Regulator.With its excellent performance and low price, it can be widely used in single-chip precision switching power supplies or precision linear regulated power supplies. In addition, TL431 can also form a voltage comparator, power supply voltage monitor, delay circuit, precision constant current source, etc.1.2 TL431 PinoutThe symbol of TL431 is shown in the Figure 1. It has three poles A, G, and K respectively (marked A, K, R on some schematic diagrams). A and K are the positive and negative terminals of the Zener diode, and the G pole is the sampling terminal.Figure 1. TL431 Pinout(1) How to determine A and K polesAccording to the schematic diagram, the A and K poles can be judged by measuring the diode with a multimeter. When measuring, set the range to RX1K gear. When the black pen is connected to the A pole and the red pen is connected to the K pole', the resistance is in a conducting state (the resistance of a common silicon diode).In addition, interchange the test leads, if the resistance is infinite, the pin connected to the black pen is the A pole, and the other pin is the K pole.(2) How to determine G poleSet the multimeter's range to Rx10k, connect the black pen to the K pole, and the red pen to the A pole. At this time, the meter should have no indication. When touching the black pen with one hand and the G pole with the other hand, the pointer should swing greatly. When this condition is met, the pin touched by the hand is the G pole.II How to Measure TL431?(1) Measurement of forward and reverse resistance of zener diodeThe multimeter range is set to Rxlk, the black pen is connected to A pole, and the red pen is connected to K pole. At this time, the forward resistance of the Zener diode is measured. To measure the reverse resistance elbow, the range should be set to Rxlk. The data measured with the MF47 meter is: the forward resistance is 6xlkΩ, and the reverse resistance should be infinite.(2) Measurement of the forward and reverse resistance of G pole and A and K polesThe multimeter range is set to Rxlk, the black pen is connected to the G pole, and the red pen is connected to the A pole. The resistance should be 35xlkΩ. The resistance of interchangeable test leads should be 10xlkn. Connect the black pen to the G pole and the red pen to the K pole. The resistance should be 11×lkΩ. If the test leads are interchanged, the resistance should be infinite.(3) Measurement of the forward and reverse resistance of K pole and A, G poleThe multimeter range is set to Rxlk, the black pen is connected to the K pole, and the red pen is connected to the G pole. At this time, the resistance is infinite. Exchange the test leads, the resistance should be 11×lkΩ. Connect the black pen to the K pole and the red pen to the A pole, and the resistance should be infinite. If the test leads are interchanged, the resistance is 8xlkΩ.Figure 2. TL431III How to Test TL431?As shown in the figure is the circuit tested by TL431. For the power supply, it is a 0~20V maintenance power supply.We connected an ammeter between the K pole and the power supply. This is done in order to clearly observe the changes in the current of the K pole as the voltage of the G pole changes. We also connect a voltmeter between K and A. In this way, we can clearly observe the changes in the output of the TL431 with the power supply.Before the test, adjust the potentiometer to near the middle value. Then, use a digital meter to measure the K pole-to-ground voltage and adjust the voltage output of the maintenance power supply. At this time, it can be found that the voltage between the K pole and the ground has only two states: one is about 2V (low level); the other is equal to the power supply voltage (high level).Figure 3. TL431 CircuitThen how to judge whether TL431 is normal?For the on-line TL431 power supply error comparator, the external maintenance power supply can be used to detect. Connect the maintenance power supply to the sampling point of the TL431, and when the voltage is higher than the nominal voltage, the TL431 will be turned on and the K-pole voltage will be low.That is to say, when the power supply voltage increases, the TL431 is turned on, so that the diode of the photocoupler is turned on, so that the transistor is in a saturated state, and the turn-on time of the primary power switch is finally shortened (reducing the duty cycle). In this way, the output voltage is reduced. If the maintenance voltage is reduced, the TL431 will be cut off, the K pole voltage will be high, and the diode of the photocoupler will be cut off, which will make the Triode in the cut-off state, and finally control the increase of the turn-on time of the primary power switch of the transformer (increase the duty cycle). Increase the output voltage. The closed-loop voltage stabilizing circuit of the switching power supply uses the TL431 on or off two states to adjust the duty cycle of the switch to control the stability of the output voltage.When measuring the multimeter, if the resistance between the poles of the lC is normal, the TL431 can be judged to be normal. When using the maintenance power supply power-on test, in the case of changing the power supply voltage, if the TL431 pole to the ground has two changes of high and low levels, the TL431 can be judged to be normal.Figure 4. TL431 Shunt Regulator ICIV TL431 Replaceable ModelsWhen TL431 is damaged, if there is no replacement of the same model, it can be directly replaced with KA431, μA431, LM431, YL431, S431, etc.TL431 suffix letters indicate product level and operating temperature range.C is commercial product (-10℃～+70℃);I is an industrial product (-40℃～+85℃);M is military product (-55℃～+125℃).V ConclusionIn summary, it is the introduction of How to Test TL431 and its Replacement.TL431 has a wide range of applications. It can be used as a precision reference voltage source, and can also be used to replace a regulator tube to form a parallel adjustable regulated power supply. It can also be used as a constant current source and voltage detection circuit. In addition, in the switching power supply, TL431 can also be used as a simple error amplifier.Component DatasheetTL431 DatasheetFAQWhat is the Use of TL431?The TL431 is a "Programmable Precision Reference" and is commonly used in switching power supplies, where it provides feedback indicating if the output voltage is too high or too low. By using a special circuit called a bandgap, the TL431 provides a stable voltage reference across a wide temperature range.What is TL431 Transistor?The TL431 is a Regulator Diode whose output voltage can be programmed by changing the value of resistors connected to it. It acts almost like a Zener diode except for that the voltage rating of this IC is programmable. It is commonly used to provide negative or positive voltage references.How does a Shunt Regulator Work?The Shunt Regulator or Shunt Voltage Regulator is a form of voltage regulator where the regulating element shunts the current to ground. The shunt regulator operates by maintaining a constant voltage across its terminals and it takes up the surplus current to maintain the voltage across the load.

IntroductionLM386 is a low voltage audio power amplifier. LM386 adopts 8-pin double in-line plastic package with a working voltage of 4V-15V. When the power supply voltage is 12V, 300mW output power can be obtained on an 8Ω load. Various oscillators can be easily produced with LM386.CatalogIntroductonCatalogI Simplest OscillatorII Blocking OscillatorIII Electronic PianoIV Square-wave OscillatorV Sinusoidal OscillatorFAQOrdering & QuantityI Simplest OscillatorFigure 1. Circuit of Simplest OscillatorIn Figure 1, the output end and in-phase input end of LM386 are connected by piezoelectric ceramic chip HTD. The amplifier forms positive feedback and generates oscillation. Here HTD is both a feedback capacitor and a sound-generating device.Component parameters in the figure: D1~D4 are 1N4001, C1=220pF, HTD is a piezoelectric ceramic sheet with an auxiliary acoustic cavity.II Blocking OscillatorFigure 2. Circuit of Blocking OscillatorAs shown in Figure 2, a simple oscillator consists of LM386, C3, C4, and loudspeakers. RP and C2 make this oscillator produce blocking- oscillation,  After connecting the power supply, LM386 does not work because the initial terminal voltage of C2 is zero, and the power supply charges C2 through RP. When the C2 charging voltage is higher than a certain value, the LM386 oscillator starts to vibrate. As the amplitude continues to increase, the current consumption of the oscillator also increases. This current flows through RP, and its voltage drop on RP also increases, causing the LM386 power supply terminal 6 pin voltage to continue to drop. Eventually, the LM386 cannot work and the oscillator stops. The power supply recharges C2 via RP again, causing the voltage at C2 to rise. When the voltage at C2 rises to a certain value, the LM386 oscillator starts again. In this way, the oscillator will produce blocking-oscillation, and the speaker emits a “beep, beep, beep” sound.Component parameters in the figure: D1~D4 are 1N4001.  C1=C3=220μF，C2=47μF.C4=0.01μF，RP=4.7K.III Electronic PianoFigure 3. Circuit of Electronic PianoFigure 3 is a simple electronic piano circuit. On pin 3 of LM386, the integrated circuit has a 10KΩ resistor to ground. This built-in resistor and ten scale resistors RP1~RP10 constitute the timing resistor of the oscillator. C2 is the timing capacitor. By adjusting the values of RP1~RP10, the speakers can sequentially emit musical sounds from low octave "do, re , mi" to high octave "do, re, mi". KI~K10 are key switches.Component parameters in the figure: Cl=C3=220μF.C2=2200μFIV Square-wave OscillatorFigure 4. Circuit of Square-wave OscillatorFigure 4 shows a square-wave oscillator composed of LM386. R1 is the timing resistor. C2 is the timing capacitor. R2 and R3 provide voltage bias for LM386 in-phase input. Because the voltage at the C2 terminal cannot change abruptly, the inverting input terminal pin  2 of the LM386 is low level, and pin 5 is the midpoint of the internal OTL output stage of the amplifier. It is 1/2Voc in a static state, and it is supplied to the third-phase input pin 3 after dividing pressure via R2 and R3. Obviously, the potential of this pin is higher than the second pin. Therefore, pin 5 outputs a high level. This high-level charges C2 via R1. When the voltage of the C2 terminal is higher than the potential of pin 3, pin 5 outputs a low level. C2 discharges to pin 5 via R1. When C2 is discharged, the potential of pin 2 drops and is lower than the potential of pin 3. Pin 5 outputs high level again. In this way, the circuit forms oscillation.  and the oscillation signal drives the loudspeaker to sound through C3.Component parameters in the figure: C1=C3=220μF，C2=0.33μF.R1=22K，R2=1K.R3=9.4KV Sinusoidal OscillatorFigure 5. Circuit of Sinusoidal OscillatorFigure 5 is a sinusoidal oscillator made of LM386. The circuit adopts Wien bridge oscillation mode, and the output signal distortion coefficient of the circuit is very low. The flashlamp H and the resistor R3 form a negative feedback circuit, which keeps the amplitude of the oscillator output signal stable and has low distortion. When the values of capacitors C1 and C2 are the same, the oscillation frequency of the circuit can be obtained by the formula f=1/2C1 R1R2. In actual production, H can use 3V, 15mA flashlamp.FAQWhat type of package does LM386 adopt?8-pin double in-line plastic packageWhat is the power supply voltage of LM386?12VWhat can be easily produced with LM386?Various oscillatorsHow does an LM386 work?The Lm386 integrated chip is a low power audio frequency amplifier, which uses low level power supply like batteries in electronic circuits. It is designed as 8 pin mini DIP package. This provides voltage amplification of 20. By using external parts voltage gain can be raised up to 200.Is lm386 an op amp?The LM386 is a type of operational amplifier (Op-Amp). ... In an amplifier circuit, the LM386 takes an audio input signal and increases its potential anywhere from 20 to 200 times. That amplification is what's known as the voltage gain.What is lm386 IC?The LM386 is an integrated circuit containing a low voltage audio power amplifier. It is suitable for battery-powered devices such as radios, guitar amplifiers, and hobby electronics projects.How do you calculate lm386 gain?Voltage Gain Analysis:Without any external components, it has a gain of Gv = 2x15K/(150+1350) = 20 (26 dB).With a capacitor (or shortcutting) between pins 1 and 8 , it has a gain of Gv = 2x15K/150 =200 (46dB).Which IC is used in audio amplifier?The IC LM386 is a low-power audio amplifier, and it utilizes low power supply like batteries in electrical and electronic circuits. This IC is available in the package of mini 8-pin DIP.What are some projects that use the LM386 audio amplifier circuit?LM 386 is an integrated class AB amp and is good for beginners small audio amplifier applications…for example in a RF receiver,small Stereo system,cheap low voltage amplifier etc…drawbacks is that it cannot handle much power and hence creates distortion when you crank up the volume too much.. So other ICs are used in practical.How to make an LM386 audio amplifier circuit?

I DescriptionAD620 is a low-power, high-precision instrumentation amplifier. Based on the information provided by the AD company, this blog introduces the characteristics and typical usage of AD620. Besides, this blog also introduces the application of AD620. The applications are mainly about photoelectric detection, ultrasonic testing, etc.Figure 1. AD620I DescriptionII IntroductionIII AD620 Pinout and Working PrincipleIV AD620 Typical UsageV AD620 Application5.1 Application in Photoelectric Detection5.2 Application in Ultrasonic TestingVI ConclusionFAQOrdering & QuantityII IntroductionAD620 is a low-power, high-precision instrumentation amplifier. And it can set the amplification factor from 1 to 1000 with only an external resistor. It is small in size, in an 8-pin SOIC or DIP package; the power supply range is ±2.3V~±18V; the maximum power supply current is only 1.3mA.AD620 has good DC and AC characteristics. Its maximum input offset voltage is 50μV, the maximum input offset voltage drift is 1μV/℃, and the maximum input bias current is 2.0nA.When G=10, its common-mode rejection ratio is greater than 93dB. The input voltage noise is at 1kHz, the peak-to-peak value of the input voltage noise is 0.28μV in the range of 0.1Hz~10Hz, and the input current noise is When G=1, its gain bandwidth is 120kHz, and the settling time is 15μs.In general, the characteristics of AD620 can be summarized as follows:AD620 can ensure the performance indicators required for high-gain precision amplification. For example, low offset voltage, low offset voltage drift, and low noise, etc.;With only one external resistor, the magnification can be set from 1 to 1000;Small size, with 8 pins;Low power consumption and its maximum supply current are 1.3mA.III AD620 Pinout and Working Principle　　The pin of AD620 is shown as in Fig. 2, its structure diagram is shown as in Fig. 3.　　　　Figure 2. AD620 Pinout　　Figure 3. AD620 Structure DiagramAD620 is a monolithic instrument amplifier. It is developed on the basis of the improvement of the traditional three-op amplifier combination.The input transistors Q1 and Q2 provide the only bipolar differential input. Due to the internal super β processing, its input offset current is 10 times lower than normal.Through the feedback of the Q1-A1-R1 loop and the Q2-A2-R2 loop, the collector currents of Q1 and Q2 are kept constant. Thus, the input voltage is equivalent to the two ends of the external resistor Rg. And the differential amplification factor from the input to the A1/A2 output is G=(R1+R2)/Rg+1.The unity gain subtractor composed of A3 eliminates any common-mode components. And then it produces a single-channel output related to the potential of the REF pin.The value of Rg also determines the transconductance of the previous stage op amp. When Rg decreases, the amplification factor increases. And the transconductance to the input transistor gradually increases. This has obvious advantages: the increase in the amplification factor increases the open-loop gain. Thus, the error related to gain is reduced. The gain-bandwidth product determined by C1, C2 and the pre-op amp transconductance increases. Thus, the frequency response is improved. The input voltage noise is mainly determined by the collector current of the input transistor and the base resistance. And the input voltage noise is reduced to  .The internal gain resistors R1 and R2 are accurately determined as 24.7kΩ. In this case, the operational amplifier gain is accurately determined by Rg.　　G=49.4kΩ/Rg+1   or   Rg=49.4kΩ/(G-1)IV AD620 Typical Usage(1) The input bias current is the current required to bias the input transistor of the op amp, and it must have a return loop. Therefore, when amplifying an AC-coupled signal source like a transformer, each input point must have a DC path to ground. As shown in Figure 4-6.　　　　Figure 4. Bias Current Loop with Transformer Coupled Input　　Figure 5. Bias Current Loop for Thermocouple Input　　Figure 6. Bias Current Loop When AC Coupled Input(2) All instrument amplifiers rectify the signal outside the channel. If a small signal is amplified, this rectified voltage becomes a DC offset voltage. The structure of AD620 allows a first-level filter to be inserted between the base and emitter of the input transistor to filter out unwanted rectified signals, as shown in Figure 5. RC=1/2πf, f is greater than or equal to the bandwidth of AD620, C≤150pF.　　　　Figure 7. Primary Filter Principle Diagram(3) The output voltage of AD620 is related to the reference terminal. Connecting the REF terminal to an appropriate grounding point can solve many grounding problems.Many data acquisition systems separate the analog ground from the digital ground. How come? Just aiming to isolate the low-level analog signal from the noisy digital environment. The grounding principle is as follows: each independent ground loop minimizes the current flowing from the sensitive point to the ground. These ground loops must be connected together at some point, usually on the ADC.Let's take a look at Figure 7. The reference terminal 5 of the AD620, the ground terminal of the sample-and-hold AD585. And the ground terminal of the analog power supply are respectively connected to the analog ground terminal of the analog-to-digital converter AD574A. The ground terminal of the digital power supply is connected with the digital ground of the analog-to-digital converter AD574A. Finally, the analog ground and digital ground are connected to the AD574A.In many applications, shielded cables are often used to reduce noise interference at the input. Proper drive to the shield can reduce the differential phase shift caused by cable capacitance and stray capacitance. And ensure that the AC common-mode rejection ratio does not drop.Figure 8 shows the differential shield drive connection.Figure 9 shows the common-mode shield drive connection.　　Figure 8. Differential Shield Drive　　Figure 9. Common Mode Shield DriveV AD620 Application5.1 Application in Photoelectric DetectionPhotoelectric detection is widely used in the industry. The principle of designing a photoelectric detection system is to reduce the total system noise to a minimum. The noise of the system mainly includes detector noise, resistance noise, and operational amplifier noise. Because they are independent of each other, the total noise can be expressed as　　Un(T)=[Un2(D)+Un2(L,F)+Un2(A)]1/2In the formula:Un2(D)———Detector noise varies with different photodetectors. The appropriate detector should be selected according to the system requirements;Un2(L,F)———Load resistance noise;Un2(A)———Op amp noise.The noise of AD620 is very small. Therefore, it is often used as the pre-op amplifier of the photoelectric detection circuit. Take the photodiode as the detector as an example to illustrate. Here, suppose the current of the photodiode is ID, then　　ID=ISC+IdarkIn the formula:ISC———Photocurrent. It is proportional to the light intensity, which is the effective information detected;Idark———Dark current. It consists of the current on the surface of the diode and the usual PN junction current. It belongs to invalid information in the system.We need to eliminate the influence of dark current. Two diodes D1 and D2 with the same performance and two resistors R1 and R2 with the resistance value of R are selected to form a bridge. As shown in Figure 10.　　　Figure 10. Photoelectric Detection Preamplifier CircuitWhen D1 has light and D2 has no light, the input voltage at both ends of the op-amp is (ISC+Idark)-R1-Idark-R=ISC-R1. It is only related to the photocurrent, thus eliminating the influence of the dark current.5.2 Application in Ultrasonic TestingIn the field of ultrasonic testing, especially when ultrasonic waves propagate in a non-uniform and attenuated medium, the echo after encountering the interface is very weak.If a general op-amp is used for pre-processing, the noise is often large and effective signals cannot be obtained. Choosing AD620 as the pre-amplifier circuit has a simple connection and low noise. As shown in Figure 11.　　　Figure 11. Ultrasonic Detection Receiving Front CircuitVI ConclusionAD620 is a high precision instrumentation amplifier. In the application, we also need to pay attention to prevent the blockage of the amplifier. If a strong DC signal is superimposed on the weak signal, we must set up a separation circuit. In this way, the DC signal can be separated.FAQWhat is AD620?AD620 is a low-cost, high-precision instrumentation amplifier. It only requires an external resistor to set the gain. The gain range is 1 to 10,000.Can I change AD620 to AD623 when making MCU products?Both AD620 and AD623 are single instrumentation amplifiers, and the pin arrangement is exactly the same.The main difference is: AD620 must use positive and negative power supplies, AD623 can be a positive and negative power supply or a single power supply.If the original board is AD620, you can replace it with 623; if the original board is AD623, you may not be able to replace it with 620 (it depends on whether the power supply of the original board circuit is dual power supply or single power supply).After replacing AD620 and AD623 in single-chip products, the program can work normally without modification.What is the difference between AD620BR and AD620AN?Their packages are different.What is the output resistance of AD620? How to adjust it?AD620 is a kind of low power consumption instrument amplifier, its output resistance is about 10K, this is the inherent characteristic of this chip, generally it is difficult to adjust.If you have requirements for output resistance, you can generally use an external circuit to solve it.Is AD620 a positive phase amplification or a reverse phase amplification?AD620 is an instrument amplifier, the output voltage is [(Vin+)-(Vin-)]*gain.If the desired signal is (Vin+)-(Vin-), the gain is positive, which is equivalent to positive amplification.Conversely, if the desired signal is (Vin-)-(Vin+), the gain is equivalent to negative, which is equivalent to reverse amplification.What is an instrumentation amplifier?Instrumentation amplifier, an improvement of the differential amplifier, has an input buffer, does not require input impedance matching, so that the amplifier is suitable for measurement and electronic instruments 

The LM1875 is a monolithic power amplifier that can provide very low distortion and high quality performance in audio applications. It uses advanced circuit design techniques to achieve minimal distortion, even at large output power levels.The LM1875 also features high gain, fast conversion rate, wide power bandwidth, large output voltage swing, large current capability, and very wide power supply range. The amplifier uses internal compensation to make it stable at gains of 10 or higher.CatalogLM1875 PinoutLM1875 ParametersLM1875 FeaturesLM1875 AppliactionLM1875 Schematic DiagramLM1875 CircuitLM1875 PackageLM1875 DocumentsLM1875 ManufacturerLM1875 AlternativesComponent DatasheetFAQLM1875 PinoutThe data sheet provided above is for your reference, so that you can understand the physical dimensions of all packages in more detail. The configuration of all LM1875 pins and the function of each pin are as follows:The function of all 5 pins and the function of each pin are as follows:Pin NumberPin NameDescription1Non – Inverting InputNon inverting end (+) of Amplifier2Inverting InputInverting end (-) of Amplifier3VeeNegative supply voltage or ground4OutputThis pin outputs the amplified signal5VssPositive supply voltageLM1875 ParametersAudio input typeAnalog InputArchitectureClass-ABSpeaker channels (Max)MonoPower stage supply (Max) (V)60Power stage supply (Min) (V)16Load (Min) (ohms)4Output power (W)20THD + N @ 1 kHz (%)0.015Iq (Typ) (mA)70Control interfaceHardwareClosed/open loopOpenAnalog supply (Min) (V)16Analog supply (Max) (V)60PSRR (dB)95Operating temperature range (C)0 to 70LM1875 FeaturesUp to 30 Watts Output PowerAVO Typically 90 dBLow Distortion: 0.015%, 1 kHz, 20 WWide Power Bandwidth: 70 kHzProtection for AC and DC Short Circuits toGroundThermal Protection with Parole CircuitHigh Current Capability: 4AWide Supply Range 16V-60VInternal Output Protection Diodes94 dB Ripple RejectionPlastic Power Package TO-220LM1875 AppliactionHigh Performance Audio SystemsBridge AmplifiersStereo PhonographsServo AmplifiersInstrument SystemsLM1875 Schematic DiagramLM1875 CircuitLM1875 PackageLM1875 DocumentsApplication NotesGuidelines for Measuring Audio Power Amplifier Performance (Rev. A)Application NotesAN-1849 An Audio Amplifier Power Supply Design (Rev. C)More LiteratureDie D/S LM1875 MWC 20-W Audio Power AmplifierLM1875 ManufacturerTexas Instruments Inc. (TI) is an American technology company that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globally. Its headquarters are in Dallas, Texas, United States. TI is one of the top ten semiconductor companies worldwide, based on sales volume. Texas Instruments's focus is on developing analog chips and embedded processors, which accounts for more than 80% of their revenue. TI also produces TI digital light processing (DLP) technology and education technology products including calculators, microcontrollers and multi-core processors. To date, TI has more than 43,000 patents worldwide.LM1875 AlternativesTDA2050Component DatasheetLM1875 DatasheetFAQWhat type of amplifier is the LM1875?Monolithic power amplifier What techniques does the LM1875 use to achieve minimal distortion?Advanced circuit design techniques What does the LM1875 use to make it stable at gains of 10 or higher?Internal compensation