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ISOW7741: VISOOUT to VISOIN and EN/FLT pin

Antoine Schnetz
Prodigy 40 points
Part Number: ISOW7741

Tool/software:

Hi all,

I want to use ISOW7741 and I am not sure I implement it correctly. Here a screenshot of the schematic.

Question 1: Is it ok to supply VISOIN with 3.3V, which are generated by TLV77133P from VISOOUT (5V) ? According to the datasheet Fig. 10-1 it should work. But I am not sure since the example has 3.3V everywhere.
Question 2: The EN/FLT pin has an internal 550kOhm pull-up to VIO. So there is no need to externally connect this pin to VIO via a pull-up resistor to be sure the converter is enabled, right ? I am not interested in the FLT feature, just want to make sure the converter is enabled.


If you see any issue with the implementation, please tell me.


Thank you in advance guys for your response

Antoine

  • +1
    TI__Expert 7235 points

    Hi Antoine,

    Thanks for reaching out. Please find my inputs below:

    Antoine Schnetz said:
    Question 1: Is it ok to supply VISOIN with 3.3V, which are generated by TLV77133P from VISOOUT (5V) ? According to the datasheet Fig. 10-1 it should work. But I am not sure since the example has 3.3V everywhere.

    Yes, this is good to go.

    Antoine Schnetz said:

    Question 2: The EN/FLT pin has an internal 550kOhm pull-up to VIO. So there is no need to externally connect this pin to VIO via a pull-up resistor to be sure the converter is enabled, right ? I am not interested in the FLT feature, just want to make sure the converter is enabled.

    Here, our recommendation is to make EN high externally as the noise coupling to EN pin if left floating can compromise the Power Converter ON State.

    Regards
    Varun