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TPS746: Current limit of TPS74601PDRVR

user6308822
Prodigy 70 points
Part Number: TPS746

Hi.

 It was confirmed that the TPS74601PDRVR used for conversion from 5.3V to 5.0V was over-current protected at about 2.4A.
The specification document states that the maximum is 1.83A, so the value is about 0.6A larger.
If the overcurrent protection value changes depending on the input / output voltage, please give me the specific calculation formula etc.
Best Regards
wanami
  • 0
    TI__Genius 14245 points

    Hi Wanami,

    Was this the DC current limit or are you referencing the maximum amount of current seen during a current limit event? Can you please provide a scope shot of the current you are referring to. 

    It is the maximum amount of current seen, then it is important to understand that current limit is a control loop which takes a finite amount of time to kick in once the output current exceeds the current limit threshold. During the time before the current limit has kicked in the current can exceed the specified current limit.

  • 0 in reply to Kyle Van Renterghem
    Prodigy 70 points

    Hi Kyle

    It sends the waveform of oscilloscope.
    This waveform converteds the current value to a voltage value, which is 100mV / 1A.
    The measurement environment is verified by electronically loading the output of the TPS74601PDRVR.
    Best Regards
    wanami

  • 0 in reply to user6308822
    TI__Genius 14245 points

    Hi Wanami,

    Thank you for the additional information. This is a very strange behavior, current limit circuits typically kick in in approximately 25us-100us and what you show appears to be showing it above the current limit for multiple seconds before it likely goes into thermal shutdown. This makes me concerned that maybe this device has been damaged. 

    Below the characterization data that was taken for the Vout=5V version device and as you can see there is no major difference with the higher input voltage and it correlates well with the graph in the datasheet for Vout=3.5V (and thus lower Vin). 

    datasheet graph