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LM358: Differential OP AMP Circuit

Gust Zhang
Expert 5811 points
Part Number: LM358
Other Parts Discussed in Thread: TLV9002, TL072H

Hi Team,

My customer use LM358 as differential op for over current protection. However they occur an issue for differential application. The blow is their schematic and issue description. Could you help check the reason for this issue?

Thanks,

Gust

  • 0
    Guru 280000 points

    The LM358 does not have rail-to-rail inputs; it requires a headroom of 2 V to the positive rail. So in this circuit, only input voltages between 0 V and 3 V are valid. For invalid input voltages, the behaviour of the output is not guaranteed.

    Use a low-voltage opamp with rail-to-rail inputs like the TLV9002.

  • 0 in reply to Clemens Ladisch
    TI__Mastermind 28476 points

    Hey Gust,

     If you would like solution with similar cost to the LM358 with a common mode range that extends to V+, you can use the TL072H. Note that this devices common mode does not go down to V-, it must be at least 1.5V above V-.

    Best,
    Jerry