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LMR23630: EN threshold

Yusuke Mukuno
Expert 7395 points
Part Number: LMR23630

Hi,

Customer have an issue  about not-match the LMR23630 enable threshold with their calculation result.

Could you please give me your advice for the reason of this issue?

Condition

Vin : 24V

RENT = 270kohm

RENB = 51kohm

VENH = 1.55V(typ), 1.7V(max)  : from datasheet

Vin_rising = 9.8V(typ)

Measurement results

Vin_rising = 13V

EN_rising = 2.1V

Muk

  • 0
    TI__Mastermind 23845 points

    Hi,

    Could you try to power up the enable from a separate supply and see what is the threshold?

    Thanks

    -Arief

  • 0 in reply to Arief Hernadi
    TI__Expert 7395 points

    Hi Arief-san

    Thank you for your support.

    Customer tried to check with EVM.

    In case of they used DC stabilized power supply, it is no issue. So, EN pin threshold is no problem.

    However, this issue occurred when they connect to their system power line.

    How do you think about the reason of this issue?

    Muk

  • 0 in reply to Yusuke Mukuno
    TI__Mastermind 23845 points

    Hi Yusuke,

    I think it is related on the delay on when the threshold of EN is reached , there will be some delay before the part is start switching. 

    If you slowly ramped EN or VIN in this case, you can see the effect of this delay is reduced and you can see the EN threshold voltage. 

    Alternatively, if you increase EN or VIN as fast as you can, you can see how long is this delay before the part is switching. 

    Thanks and i hope that answers the question

    -Arief