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TPS7A39: TPS7A3901 about INN pin

Masazumi Ishii
Genius 3945 points
Part Number: TPS7A39
Hello.

I have a question about TPS7A3901.
For details, please check the attached materials.

Thank you.TPS7A3901-3.pdf
  • 0
    TI__Guru 50190 points

    HI Ishii-san,

    Can you capture a scope trace of the INP and INN pin with respect to GND during this power-up procedure? Your detailed power-on procedure mentions that power is OFF before the CN4 connection, is there any chance it was ON before the connection?

    Also, you mention that you have 4 TPS7A39's in parallel. Are the failures at the same location or is it random?

    I have not seen the TPS7A39 fail before so I would like to get more information to help understand what might be happening.

  • 0 in reply to JCHK
    Genius 3945 points
    Hello

    Thank you for your reply.
    The input waveform is attached.
    The cause is unknown, but there seems to be a problem with the input waveform.

    Thank you.TPS7A3901-4.pdf
  • 0 in reply to Masazumi Ishii
    TI__Guru 50190 points

    HI Ishii-san,

    Is there any chance that there is a residual charge on the connector when CN4 is attached? I am just speculating here, but if there is a residual charge and some pins make contact before GND, maybe some unanticipated ground loops are being created upon insertion. Can you take a scope shot at the time of CN4 insertion?