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op amp internal input protection

Tony Piazza
Prodigy 140 points
Other Parts Discussed in Thread: OPA192

I need an op amp with dual supplies 12V to -12V and has input overvoltage protection (30V to -30V) and also has protection against applying an input voltage before power up. Will OPA192 do it? If not, is there such a thing? Preferably SMD.

  • 0
    TI__Intellectual 2155 points
    Hello Tony,

    I recently answered a similar question about overvoltage on the input pins of an opamp. The suggestions in the thread below are also applicable to your situation:

    e2e.ti.com/.../530650

    The only concern i see in your application is your power supply impedance and whether or not your power rails can sink and source currents even when they are disabled. If you have a schematic of your opamp + supply I could give you a better answer.

    Best Regards,
    Mihir Gupta
    Field Applications Engineer
    Texas Instruments
  • 0 in reply to Mihir Gupta65
    Prodigy 140 points
    Thank you Mihir. I have several amps on one board. I have inverting, non inverting and summing. Some have an input resistor and some don't though I can add one if you think it is a good idea. I am more concerned about the user applying a voltage to the inputs before the amps are powered up. All the amps have a + and - 12V rail. The supplies can handle 150W.
  • 0 in reply to Tony Piazza
    TI__Intellectual 2155 points

    Hi Tony,

    If the user applies a voltage to your inputs before power-up, the internal ESD diodes will forward bias. If your power supply rails (when they are not powered up) have a path to ground through which the current can flow, then all you have to do is limit the current. If the power supply rails do not have a path for the current, then your power supply rails are floating, in which case it is harder to predict what path the current will take.

    Regards,

    Mihir

  • 0 in reply to Mihir Gupta65
    Prodigy 140 points
    Thank you Mihir. You have answered my question. I will contact the power supply manufacturer.