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Original question:

TPS40425: TPS40428 compatibility with TPS40425

TPS40425: Thermal behavior

Mike Yu
Expert 1830 points
Part Number: TPS40425
Other Parts Discussed in Thread: CSD95372BQ5M, TPS40428

Hi Team,

The customer report that the TPS40425 will enter the OTP when the device is only 60 degrees, we think that it should be they add the pull low resistor (PR6 and PR30) on the TSNSx pins. Would you help to check following item? Thank you.

  1. Do we need the pull low resistors  (121K ohm) PR6 and PR30 on TSENx pin when uses P-stage CSD95372BQ5M and uses extra BJT to sense the temperature? (Can we remove PR6 and PR30 ?)
  2. Can we remove PQ27, PQ28 to disable OTP function? Will there be other problems?
  3. May I know the voltage conditions for OTF triggering in TSNSx pin?
  4. If we change controller to TPS40428 (uses smart power mode), is that BOM change only without re-spin? (as reference design without extra BJT : https://www.ti.com/lit/df/tidrlb6a/tidrlb6a.pdf?ts=1640086024847 

Best regards,

Mike

  • 0
    TI__Mastermind 26300 points

    Hello,

    Sorry, for the delay due to illness. I'm working on it and post my answer today.

    Regards

  • 0 in reply to Mahmoud Harmouch
    TI__Mastermind 26300 points

    Hello, here is my comment:

    1. Do we need the pull low resistors  (121K ohm) PR6 and PR30 on TSENx pin when uses P-stage CSD95372BQ5M and uses extra BJT to sense the temperature? (Can we remove PR6 and PR30 ?)

    Answer: pull down resistors on TSENx pin is not recommended. There should be only BJT. The pull down resistor can cause the earlier overtemperature. The current source is distributed between the pull down resistor and the BJT. The small portion current into the resistor develops a small voltage and device can understand it as high temperature.

    1. Can we remove PQ27, PQ28 to disable OTP function? Will there be other problems?

    Answer: I do not think the BJTs are the issue. Leave it floating if not used

    1. May I know the voltage conditions for OTF triggering in TSNSx pin?

    Answer: with BJT, assume the voltage is 500mV at 25C and changes of -1.45mV/C. The OTF is programmed through the OT_FAULT_LIMIT

    1. If we change controller to TPS40428 (uses smart power mode), is that BOM change only without re-spin? (as reference design without extra BJT 

    Answer: BOM is the same for both parts.

    Please close this thread as resolved if your questions are answered.

    Regards

  • +1 in reply to Mahmoud Harmouch
    Expert 1830 points

    Hi Mahmoud,

    Thanks for the feedback, let me check with the customer. If there is no further question, I will close this post.

    Best regards,

    Mike