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OPA1637: PD input termination

Errol Leon6
Expert 5830 points
Part Number: OPA1637

Hi team,

My customer is using the OPA1637 in an audio preamp, and the datasheet is giving conflicting information on how to terminate /PD input (powerdown) when powedown is not used.

Some examples and text tell them to tie to V+ rail, and others tell them to simply float it.

To the customer it seems that /PD is internally "pulled-up" by a current source, so they are not sure why so many examples show it tied to V+ rail.

Are there any specific benefits tying to rail if not used or can I just float it?

Thank you in advance for your support!

Errol

  • 0
    TI__Mastermind 21510 points

    Errol,

    I have reached out to our team to get an answer. I will update you with clarification by tomorrow. 

  • +1
    TI__Mastermind 21510 points

    Errol,

    I have reached out to our systems team and indeed there is conflicting information. We have concluded that although the pin is internally pulled up as you mentioned it is best to tie to the rail if this pin is not being used. Some customers will place large caps on this PD pin for noise immunity. Let's say that the pin was seen as a low in this case (cap charging). Well considering the note below the input current could exceed the 10 mA spec and damage could occur. So therefore if it is not in use, tying to the rail will prevent such a condition.