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ISO7231C error

Other Parts Discussed in Thread: ISO7231C, ISO7631FC

Hello e2e,

The problem has been tracked down to the ISO7231C part. The pulse does seem to happen when the 5V Iso Rail VCC2 falls but it is only 500 nSeconds in duration instead of 1 or 2 mSec. This doesn’t happen when I shut off the VCC2, 5V isolated supply.  I did find that grounding EN2, pin 10, and disabling the part does prevent the pulse. I tried the same thing on EN1, but the pulse still persisted.  

Right now I’m wondering if I could replace the ISO7231 with a ISO7241 to pass a quick reset/disable signal through and shut of EN2.  I have a feeling that using a part to send its own reset signal probably isn’t a good idea though.

Thank you for your help

  • Hi Natallia,

    ISO7231C is a failsafe high part. Its outputs go to high when the input side power is lost. This may be the reason why you are seeing the output (high?) pulse of 1 or 2 msec duration. Though I am not sure why the pulse is going low again - it should have stayed high unlsess VCC2 going down after that time?

    You might consider the ISO7631FC which is a failsafe low part, and whose outputs will go to zero when input supply is lost.

    Rgds,

    Anant