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ISO6740: ISO6740 and ISO6741 ORING usage

Koji Ikeda
Expert 5545 points
Part Number: ISO6740
Other Parts Discussed in Thread: ISO6741,

Hello Support team,

My customer need 3ch forward only and they would like to design to use either ISO6740 or ISO6741, due to delivery risk. They ask questions.

*Can NC pin connect to GND? Is this no connection to chip internally?

*Can EN1 be floating? Does this pin has internal pull down? Datasheet show EN1 low when high impedance.

Thanks,

Koji Ikeda

  • 0
    TI__Guru 52190 points

    Hi Ikeda-san,

    Thanks for reaching out.

    Koji Ikeda said:

    *Can NC pin connect to GND? Is this no connection to chip internally?

    Yes, NC pins can be connected to GND without any issues as they are internally not connected to any circuit.

    Koji Ikeda said:
    *Can EN1 be floating? Does this pin has internal pull down?

    ENx pins have internal pull-up resistors (550kΩ) and hence, the respective outputs will be enabled by default. Although it is perfectly fine to operate the device by floating ENx pins, if customer application has noisy environment then we recommended that these pins are pulled-up through a strong pull-up resistor externally. Thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    TI__Expert 5545 points

    Koteshwar-san,

    Thank you for your support. Please let me confirm,

    ISO674x datasheet shows "in high-impedance state when EN1 is low."  this looks like to be internal pull down, does this have internal pullup and enabled as default?

    Thanks,

    Koji Ikeda

  • +1 in reply to Koji Ikeda
    TI__Guru 52190 points

    Hi Ikeda-san,

    Thanks for further seeking clarification.

    The statement from pin function table (also copied below) for ISO674x states two things, as listed below,

    • Outputs will be enabled when ENx pin is HIGH or OPEN
    • Outputs will be in high-impedance (same as disabled) when ENx is LOW

    Figure 9-3 also shows that ENx pin has internal pull-up of 550kΩ, also copied below.

    Hence, the outputs are going to be enabled when ENx pins are left floating. I hope it is clear now, thanks.


    Regards,
    Koteshwar Rao