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TPS7A4101: Current limit

Genius 16345 points
Part Number: TPS7A4101

Hello,

My customer has an question for current limit of TPS7A41.

Is the current limit Brick-wall type or Foldback type?

Regards,
Oba

  • Hi Oba, 

    This part's current limit is a Brick-Wall Type. 

    Best,

    Juliette

  • Hello Juliette,

     

    My customer tested the current limit function.

     

    The current limit started at 154mA (VIN=21V)

    Then it recovered from the current limit condition when the current went down to 113mA.

    So they felt this device should have foldback current limit.

    How to think about this behavior?

     

    Regards,

    Oba

  • Hi Oba, 

    Typically when a device has a Foldback current limiting feature, it is highlighted in the data sheet with multiple plots. In the absence of those plots, Brick-wall current limiting is assumed. 

    As for the device dropping current from 154mA to 113mA, for a foldback current limiting device, the short circuit current is much lower than the maximum output current. 

    For this device:

    The current limit can be triggered anywhere from 51mA to 200mA. 

    So either:

    1. After the current limit was triggered, it dropped down to it's typ. current limit value for this input voltage.

    or

    2. The part was in current limit for too long, and it triggered a thermal shutdown, where the output could have cycled on and off. 

    Does the customer have a scope shot of the output current? 

    This App note titled Know Your Limits  describes current limit on page 2 and 3 and the distinction between the 2 types.

    Best,

    Juliette