This board is built using a 2 x INA149 precision unity-gain difference amplifier with a very high input common-mode voltage range. The project can be used as a current sensor for high-voltage applications, INA149 provides a common-mode voltage range of +/-275V. The project operates with a wide supply range from +/-5V to +/-15V. The circuit measures current by sensing the voltage drop across a series of resistors RS, R4, and R12. The application circuit shows the INA149 used to measure the supply currents of a device under test. The sense resistor imbalances the input resistor matching of the INA149, thus degrading its CMR. Also, the input impedance of the INA149 loads RS, causes a gain error in the voltage-to-current conversion. Both of these errors can be easily corrected.
This board is built using a 2 x INA149 precision unity-gain difference amplifier with a very high input common-mode voltage range. The project can be used as a current sensor for high-voltage applications, INA149 provides a common-mode voltage range of +/-275V. The project operates with a wide supply range from +/-5V to +/-15V. The circuit measures current by sensing the voltage drop across a series of resistors RS, R4, and R12. The application circuit shows the INA149 used to measure the supply currents of a device under test. The sense resistor imbalances the input resistor matching of the INA149, thus degrading its CMR. Also, the input impedance of the INA149 loads RS, causes a gain error in the voltage-to-current conversion. Both of these errors can be easily corrected.
The board provides dual options for current sense resistors. Users may use THT resistors up to 3W R3, R11, or SMD 2512 R4 and R12 Up to 3W. The default circuit measures current up to 2A. Choose the appropriate current sense resistor for a higher or lower current sense range.
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