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OPA2171: Application and schematic Review

Part Number: OPA2171
Other Parts Discussed in Thread: OPA2991

Hi team,

Could you please help us review below customer's OPA2171 circuit schematic? The high value of resistors provide isolation function here. 

Best Regards,

Stanley Dai

  • Hi Stanley,

    Why is the customer not using the OPA2991 instead?

    The customer has switched in IN- and IN+ connections. This means they are using positive feedback! They need to switch the connection so the feedback connection connects to the IN- input.

    They also have the positive power supply pin connected to GND and the negative power supply pin connected to +5V. This will damage the device! The positive power supply pin should connect to +5V and the negative power supply pin should connect to GND.

    Is there a capacitor at the Isense node? Once I have this information I can perform a stability analysis for you.

    Lastly, the output will not be able to swing all the way down to 0V with a 0V input due to the output swing limitations of the device.

    Thank you,

    Tim Claycomb