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THS4131: THS4131 Input Differential Voltage Max

JIM REAL
Prodigy 20 points
Part Number: THS4131

Hi,

Simple, and maybe silly question: the data sheet for the THS4131 part shows a +/- 6V max input differential voltage (Table 7.1).  I'm wondering if that's truly the case when operated with feedback and powered by +/- 15V rails?  I would like to apply +/- 10V inputs.  When I think of how an op-amp works with feedback, the 2 inputs are at virtual ground, so a true differential voltage present at the pins never occurs.  So does this statement about +/-6V refer to a differential voltage present at the input pins, or does it refer to the differential voltage of an input signal that is present on the other side of input resistors?

Thank you. 

  • 0
    TI__Genius 15975 points

    Hi Jim,

    Yes, you are right that it is difficult to achieve a +/-6V max input differential voltage with feedback (RF) and gain setting (RG) resistors. In normal operation with feedback and gain resistors, the device inputs are at virtual ground and hardly see any difference voltage. This statement applies to the differential voltage present at the input pins and not to the differential voltage present before the input resistors. So, you can easily apply +/-10V inputs before the gain setting resistor (Rg).

    Some applications like clock buffers, where the FDA could be used in open-loop conditions without feedback and gain setting resistor, it is necessary to limit the input difference voltage so as to prevent the ESD diodes from turning on. This specification is mainly catered to such applications.

    Best Regards,

    Rohit

  • 0 in reply to Rohit Bhat
    Prodigy 20 points
    Great,
    Thank you Rohit for your reply. That helps very much.