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TPS40210: TPS40210 keeps resetting while there is no overcurrent event

Peng Liu50174
Expert 1510 points
Part Number: TPS40210

Hi,

We are using TPS40210 to generate 26V supply from 15V input.

Sometimes, we found that the output can't reach to 15V. There is no voltage spikes on pin-7 ISNS for overcurrent detection observed. But we do see that the regulator pin-2 SS is oscillating, meaning it is resetting the output continuously.

Is there any other situation under which TPS40210 resets its output even without output over current?

Peng,

  • 0
    TI__Mastermind 21720 points

    Hello Peng,

    Thanks for reaching out with your questions and for using the TPS40210.

    Is the boost topology being used in this design? If that is the case the output voltage should be 15V as soon as the power is applied.

    Is the gate driver switching when the SS pin is pulled low? What is the load current when you are trying to start-up?

    There are only a few ways that the SS pin will discharge. One is the over current protection. Two is if the DIS pin is pulled high and the last is if the input voltage is less than 4.5V.

    Let me know if you have any questions.

    Garrett

  • 0 in reply to Garrett Roecker
    Expert 1510 points

    Hi, Garrett,

    Yes, we are using the boost topology.

    After power up, the output is 15V w/o enabling the TPS40210.

    WhileTPS40210 is enabled, the DIS is always low driven by the host controller, and the input 15V is constant,

    The load current is limit to 2A.

    What is the minimal width of the signal on ISNS to trigger TPS40210 over-current protection?  There is only TBLNK Leading edge blanking 75ns at page 5 of the datasheet, but no overcurrent propagation delay time.

    Peng,

  • 0 in reply to Peng Liu50174
    TI__Guru* 78320 points

    Hi Peng,

    Thank you for the explanation.  Yes the delay time is also related to external circuit including the RC filter at the current sense pin.  Once it is triggered it will immediate enters the protection mode, so the delay should not be longer than a switching cycle. 

    Hope this explains.  Please note that we are able to offer follow-on support next week. Wish you a happy Thanksgiving!

    Thanks,

    Youhao Xi, Applications Engineering