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ISOW1412: Power up sequence

Oba
Genius 17435 points
Part Number: ISOW1412


Tool/software:

Hello,

 

My customer has a question for power up sequence of ISOW1412. 

Now VDD=5V and VIO=3.3V. 5V is powered up before 3.3V power up.

According to Table10-1 on P32 of the datasheet, ”VDD>UVLO+ and VIO<UVLO+” condition is invalid operation for VISOOUT.

They want to understand the meaning of this “invalid operation”.

Should they avoid this condition, meaning they have to change the power sequence to 3.3V 1st and 5V 2nd?


Regards,
Oba

  • +1
    TI__Expert 8430 points

    Hi Oba-San,

    Thank You for Reaching out.

    Yes, that is correct. VIO should be powered up before VDD in order to get a regulated VISOOUT. The Invalid Operation here means that VISOOUT Values will be unknown in this scenario.

    As you stated, yes they will have to reverse the VDD and VIO sequence. First Power up the VIO to 3.3V and then VDD to 5V.

    Regards
    Varun