Description
3-5.5V AD623 AD620 Millivolt Amplifier Microvolt Signal Amplifier Rail to Rail Instrumentation Amplifier Module
Product Description
Dedicated instrumentation amplifier core, rail-to-rail output, high input impedance, high common mode rejection ratio, low offset and drift, low noise, and high closed-loop gain stability, the best choice for measurement/amplification.
Feature
1. High-end dedicated instrumentation amplifier AD623 core 2. Single power supply, support 3-5.5V power supply 3. Integrated negative pressure generation module, dual power supply operation, easy to deal with negative signals/AC signals. 4. Power input LC filter, pure and stable, to ensure the stability of signal amplification. 5. Built-in negative voltage generation module, only need single power supply to operate dual power supply, simplifying system design. 6. Rail-to-rail output, output swing up to +-VCC, far exceeding the core products such as LM358/AD620 (only up to VCC-1.5V) 7. The magnification is adjustable from 2-1000 times to adapt to different applications. 8. The module is concise, extensible, detailed description, convenient for secondary development.
Specification
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item
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value
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Amplifier type
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dedicated instrumentation amplifier AD623 core
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Input range
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0.5VCC (that is, the voltage between S+/S- is less than half of the power supply voltage.)
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Output range
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+-VCC (rail to rail)
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Magnification
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2-1000 times adjustable.
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Power consumption
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150uA (typical) 650uA (maximum)
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Power supply
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3-5.5V
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Gain accuracy
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0.35% (G>2) 0.10% (G=2)
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Input offset voltage
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100-200uV
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Input offset drift
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1uv/℃
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Common mode rejection ratio
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800KHZ
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Gain bandwidth
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90db
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PCB size
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40*23mm, with 4 M3 mounting holes
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Installation Instructions
It is recommended to use a smaller magnification (such as 50/100 times) to test the baby, and then adjust it to the required multiple. Adjust the A++ knob clockwise to increase the magnification (up to 1000 times). When it is adjusted to a large value, you can hear a slight click from the potentiometer, which means that the adjustment has reached the end. You can also use a resistor to fix the magnification, so the magnification value will be more stable.
Precautions
1. Some people call REF a zero-adjusting pin. This is no problem. However, the accuracy of the AD623 core is very high. If REF is directly grounded, the output is very close to 0, and no adjustment is actually required. It is recommended to adjust the REF pin voltage only when the voltage needs to be shifted 2. This shop uses imported American bounds potentiometers, which are uniformly adjusted, stable, and highly reliable. The price is 10 times higher than domestic potentiometers, which are not comparable to ordinary domestic potentiometers. 3. The offset voltage of AD623 is 200uv, that is, the maximum error of 200uv may be generated in the input voltage. Therefore, if the input voltage is smaller, the initial error generated is greater. It is recommended that the signal should not be lower than 3mv. 4. The 3db gain bandwidth of AD623 is 800KHZ, that is, gain multiple * frequency = 800KHZ. Therefore, if the DC signal is amplified, the maximum can reach about 1000 times. If it is amplified 800 times, the signal should not be higher than 1KHZ. If it is amplified by 10 times, the signal should not be higher than 80KHZ, and so on, the higher the signal frequency, the greater the amplification loss. 5. The maximum adjustment range of the REF terminal should not be too large, otherwise it will affect the magnification. 6. The output voltage range of the amplifier is restricted by the power supply voltage. The linear zone of our AD623 module reaches ++-VCC. When amplifiers such as AD620/LM358 are powered by +5v and -5V, the linearity is only between -3.6V and +3.6V. 7. The REF pin of AD623 can only pull up/down the output voltage. Generally grounded. When you need to use the REF pin to raise or lower the output, you can change the voltage of this pin. But in this case, it should be noted that the linear region of the magnification will not change due to the change of pin 5, and its maximum output will not exceed VCC. Common sense of instrumentation amplifier: For various non-electricity measurement, the sensor usually converts it into a voltage (or current) signal. The voltage signal is generally weak, the smallest is 0.1μV, and the dynamic range is wide, often with a large common mode interference voltage . Therefore, most of the instrumentation amplifiers need to be connected behind the sensor. The main function is to perform precise voltage amplification on the sensor signal and suppress common-mode interference signals to improve the quality of the signal. In general signal amplification applications, a differential amplifier circuit is usually required to amplify the signal before acquisition. However, the basic differential amplifier circuit has poor precision, and the resistance matching problem is the main factor affecting the common mode rejection ratio. If a discrete operational amplifier is used as the measurement circuit, it is inevitable that there will be differences in resistance, and the variables that affect the accuracy of the entire signal amplification will be more complicated, resulting in a reduction in the common-mode rejection ratio and nonlinear gain. The integrated instrument amplifier made by the post-mold technology solves the above matching problem, and the instrument amplifier circuit does not have the above shortcomings, so it is widely used. Because the sensor output impedance is generally very high, the output voltage amplitude is small, and the working environment is harsh, the instrument amplifier has its special requirements compared with general general purpose amplifiers, which are mainly manifested in high input impedance and high common mode rejection. Ratio, low offset and drift, low noise, and high closed-loop gain stability. The general integrated instrument amplifier has the following characteristics: (1) The input impedance is high, generally higher than 109Ω (2) Low bias current (3) High common mode rejection ratio (4) Balanced differential input (5) Good temperature characteristics (6) Adjustable gain (7) Single-ended input
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