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TPS54361: Current Limit Temperature Drift

Shota Mago
Expert 8130 points
Part Number: TPS54361

Hi team,

My customer considers to use TPS54361  for his end product and provided a question.

According to Figure4 in the datasheet, the current limit seems to be higher at lower temperatures and lower at higher temperatures.

  1.  Is there some device which has inverse trend(the current limit becomes lower at lower temperatures and higher at higher temperatures) because of lot variation?
  2.  Is the temperature here(Figure4) Ta or Tj?

Best regards,

Shota Mago

  • 0
    TI__Mastermind 34775 points

    Hi Shota,

    1. Higher current at high temp may cause reliability issue because of the positive feedback of higher temp---->higher current limit----->higher power loss------>higher junction temp------>even higher current limit. so this feature is not a good for converter.

    2. It's junction temp on Fig 4.

    B R

    Andy

  • 0 in reply to Andy Chen
    TI__Expert 8130 points

    Hi Andy,

    Thanks for your quick response.

    As for question no.1, my expression was not good.

    As you mentioned, higher current at high temp is not good because of positive feedback.

    So the customer would like to know "Is there some possibility that TPS54361 has higher current limit at high temp characteristics because of variation?".

    Best regards,

    Shota Mago

  • 0 in reply to Shota Mago
    TI__Mastermind 34775 points

    Hi Shota,

    The current limit at 150C is about 4.95A typical, and the minimum is 4.5A, we can assume the current limit variation at 150C is 4.95+/-0.45A, so the higher limit is possibly 5.4A

    B R

    Andy

  • 0 in reply to Andy Chen
    TI__Expert 8130 points

    Hi Andy,

    Let me clarify my question.

    According to Figure.4, current limit becomes lower at high temperature(150C) and becomes higher at low temperature(-40).

    Does all of TPS54361 show this characteristics regardless of device to device variation?

    In other words, TPS54361 which has inverse characteristics(current limit becomes higher at high temperature(150C) and lower at low temperature(-40C)) never come out. 

    Is this understanding correct?

    Best regards,

    Shota Mago

  • 0 in reply to Shota Mago
    TI__Mastermind 34775 points

    Hi Shota,

    Yes, this is because that all IC has fully same die material and circuit design,  no chip of TPS54361 will has inverse characteristics of current limit as you mentioned.

    B R

    Andy

  • 0 in reply to Andy Chen
    TI__Expert 8130 points

    Hi Andy,

    I understood.

    Thanks for your quick response!

    Best regards,

    Shota Mago