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ISO7041: IN/OUT Not Used - Pull-up or pull-down?

Trenton Reed
Intellectual 2990 points
Part Number: ISO7041

Hi Team,

There is one channel which will not be used in the design. To have the lowest power consumption, should the IN pin be a no connect, pull-up, or pull-down resistor? The default output is high and from https://e2e.ti.com/support/isolation-group/isolation/f/isolation-forum/732667/faq-can-channel-input-output-pins-on-a-digital-isolator-be-left-floating  it says we should do a pull-up. Can you confirm this is true for ISO7041?

Does there need to be a pull-up on both input & output pins?

Do you have an idea of how much this will save with power consumption?

Thank you,

Trent

  • +1
    TI__Genius 14495 points

    Hello,

    Thank you for your questions.

    The ISO7041 (non-F version) has a default state of HIGH. This means that the input pin can be connected to a pull-up resistor in order to maintain the default state and allow for lower current consumption.

    As mentioned in the FAQ you have linked, the unused output pins can be left disconnected and no resistive load is needed.

    In terms of the current consumption of the device, please see the image below for more information (Table 7.10 from the datasheet):

    The highlighted portions show the current consumptions of the device when there is DC supply, e.g. pull-up resistor to input pin. Please make sure you look at the section pertaining to how the refresh enable pin is connected for your application (enabled is top section, disabled is bottom section).

    Regards,
    Aaditya Vittal