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[ OPA3693 ] Device Heat Up and Broken Problem

Other Parts Discussed in Thread: OPA3693

Hello,

My customer is now designing their board with OPA3693, however during evaluation,they are facing some problems that the device is heated up and sometime broken.

Here are some conditions.

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Customer has recognized, when device is powered up, there is some delays between -5V and 5V.
In practice, -5V ramp up around 1mS faster than 5V.
Does this be any problem? If so, do you have specification on power sequences?
Here are some findings focus on power supply sequences.
  • No input and output signal are connected
  • Power is supplied from DC power supply equipment with current limit (prevent damage)
  1. In case -5V  is NOT connected (means -Vs is left open), then when 5V is applied, excess current is drawn by 5V railand voltage dropped due to current limit of power supply equipment.
  2. When -5V is connected (still NOT supplied), device operate correctly.
We suspect that ESD protection circuit could affect, but not sure at this moment.
It's greatly appreciated, if you can explain what happen on this board.
Thank you for your support in advance.
Please let me know at off line, if you need more information.
Thanks,
Ken
tanaka-k@clv.macnica.co.jp
  • I see on your schematic that there are 10uF supply bypass capacitors on the power supply.  Are these electrolytic capacitors?

    There should be low ESR (equivalent series resistance), ceramic 0.1uF bypass capacitors on each supply pin.  I do not know if these capacitors are part of the observed issues or not, but it is possible the amplifier is oscillating. 

    Is it possible to find where the high current is flowing when the -5V pin is not connected?  It is really hard to say how the device will operate with +5V connected and -5V floating. 

  • Hi Loren,

    Thank you for your reply.

    Can we talk more in off line? I can explain background more and share their schematics and findings.

    Can you please send an e-mail to tanaka-k@clv.macnica.co.jp?

    Thanks,

    Ken