• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 31 subscribers
  • Views 664 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Bypassing lm4861 Outputs

Chris DeWitt
Prodigy 90 points
Other Parts Discussed in Thread: LM4861

We use an LM4861 in a system where the speaker is off board and I need to harden it from ESD coupling.  I'd like to bypass the amplifier output at the connector with some 0.1uF caps to ground but don't want to risk instability in the amplifier. 

Is this a problem?

Thanks,

  • 0
    Intellectual 860 points

    Perhaps I am not understanding correctly, but I would suggest using clamping diodes or transorbs on the output if ESD is a concern.  The capacitance can be kept quite low and you can achieve a high level of protection.

    Tim

  • 0 in reply to Tim Sobering
    Prodigy 90 points

    Tranzorbs are great a solution if you have direct conduction of the discharge current.  In this case the parts are all enclosed and there is no way to touch any of the wires but there are several inches of wiring between the board and the speaker and if there is a discharge in the vicinity the field from that discharge can couple into the wiring, through the active components and onto the power bus.  Normally I'd bypass the connector pins at the connector to keep the coupled currents off the signal lines but in this case it means putting caps on the output of a high gain amplifier.  I’ve known many amplifiers that tend to oscillate if you do that but I don’t know about this one.

  • 0 in reply to Chris DeWitt
    TI__Expert 3350 points

    Chris,

    The LM4861 oscillates with 0.1uF to GND at the outputs.  You could isolate the amp output from the capacitance.

    Regards,

    royce