ADuM1400 VDD2-GND2 voltages when VDD2 is NOT supplied

My customer reported as follows. Would you teach me what happened inside ADuM1400.

He didn't mount side2 PINs

He supplied 3.3V between VDD1 and GND1.

when he measured the voltage between VDD2 and GND2, it was 0.62V

I believe the circuit in side1 is active and the circuit in side2 is NOT active.

why did he observe 0.62V between VDD2 and GND2?

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  • Hello,

    This is expected behavior for the oldest series of devices.  The previous answer is correct, the refresh and data signals run constantly and have an inductive coupling path for a small amount of power to be transferred.  This is because these older devices were built to minimize operational power overhead in the receiver circuits.

    The power transferred in the newest architectures is much lower due to a fully differential receivers.  If this small voltage is problematic in your system, I would suggest switching to the ADuM140E, it is a drop in replacement, and that leakage should be very small.

    Another option that is not drop in, but very low power is the ADuM1440.  It provides much more control of the refresh circuit as well.

    Best Regards,

    MSCantrell

  • Thank you for your reply.

    I like to confirm one more thing.

    the customer said as follows.

    Is this the same reason and can he fix this problem when he use ADuM140E or ADuM1440?

    He supplied 3.3V between VDD2 and GND2.

    when he measured the voltage between VDD1 and GND1, it was 0.12V

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