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ISOW7842: Power Supply for ISOW7842

Lenna Yan
Intellectual 1960 points
Part Number: ISOW7842


Hi Team,

we are facing an issue when using ISOW7842. The VCC is 3.9V, while the Viso is 0.9V and the input current is 0.16A. There are three options for the power supply, the input voltage is 5V or 3.3V. Could you tell if the isolated power supply can operate well when the input voltage set to 3.9V ? Please refer to the below schematic.

  • 0
    TI__Expert 6955 points

    Lenna,

    The ISOW7842 needs Vcc to be within 10% of 3.3V  in order for Viso to be 3.3V. Vcc also needs to be within 10% of 5V for the 5V to 5V/3.3V configuration.

    Respectfully,

    Lucas

  • 0 in reply to Lucas Schulte9
    TI__Guru 55885 points
    Hi Lenna,

    Could you please share us more details about the issue? Can you please also share customer schematic? What is the load connected at VISO? Any more information in this regard will be helpful to understand more about the customer issue. Thanks.


    Regards,
    Koteshwar Rao
  • 0 in reply to Koteshwar Rao
    TI__Guru 55885 points
    Hi Lenna,

    Thanks for sharing update on this customer issue, offline. To summarize our internal discussion, customer had used a normal diode between VISO and GNDISO pins instead of using an LED diode for power indication. This had caused the voltage at VISO pin to drop to 0.9V, after removal of the normal diode I understand that everything is working fine.

    I will go ahead and mark this E2E post as closed, thanks again.


    Regards,
    Koteshwar Rao