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TPS25833-Q1: NTC

Mehmet COBAN
Intellectual 275 points
Part Number: TPS25833-Q1

Hi Kuno,

I am using TPS25833-Q1 IC. My project is 2x12W Type-C. The problem is my board cannot working continuously when the operating temperature is 85C. It is going to shutdown mode when the IC's temperature is 142C.

I wonder if I would change the NTC, for example may be I can short to ground or put a resistor which has different value, may it improve the thermal performance? can increase the temperature of entering thermal shutdown temperature?

Thanks!

Mehmet COBAN

  • 0
    TI__Expert 8980 points

    Hi, Mehmet,

    Kuno is in holiday and will back to office tomorrow. He will follow up your question tomorrow.

    Here I provide you a quick feedback. The TPS25833-Q1 has two thermal protection scheme. One is based on NTC pin voltage and another is junction temperature. The NTC shutdown threshold can be adjusted by external components but the junction temperature thermal shutdown threshold is fixed.

    1. NTC based thermal shutdown

    2. Junction based thermal shutdown


    Thank you,

    Bob

  • 0 in reply to Bob Ma
    Intellectual 275 points

    Hi Bob,

    Thank you for your answer. I knew these specifications too but my question is can I increase the NTC based thermal shutdown temperature If placing larger than 470k ohm resistor, such as 1 megaohm? 

    I did not read related equation about NTC based thermal shutdown resistor calculation in the datasheet.

    Thanks,

    Mehmet ÇOBAN

  • 0 in reply to Mehmet COBAN
    TI__Mastermind 18556 points

    Hi Mehmet,

    I know what you mean, actually you can short the TS pin to ground or put a resistor which has different value, this action will change the TNTC_WARN and TNTC_TSD, but in my opinion the TNTC_TSD can not exceed the thermal shutdown value ( 160 Celsius typ).For example, if you short the NTC pin to GND, then you will obtain a only one thermal shutdown value, it is the 160 Celsius typ, do not have the TNTC_WARN and TNTC_TSD.

     

    Best Regards,

    Kuno.

  • 0 in reply to Kuno Wu
    Intellectual 275 points

    Hi Kuno,

    Thank you for your answer. I like working with you and with Bob.

    I understood you but when I added a Rntc, devices entered the shutdown mode around 142C. Then I shorted to NTC pin to GND and retested. Now, devices are entering the shutdown mode (as you mentioned this mode is IC' s own mode) at 154C. I think it is normal. 

    But I wonder if I put a Rntc resistor 1megaohm rather than 470k ohm, can I increase the NTC based thermal shutdown temperature (it was 142C). 

    I think, your idea is putting another resistor cannot change the "NTC based thermal shutdown temperature (it was 142C)". Am I correct Kuno?

    Best Regards,

    Mehmet

  • +1 in reply to Mehmet COBAN
    TI__Mastermind 18556 points

    Hi Mehmet,

    No, actually change the resistor can change the TNTC_TSD value, because this value is depending on the voltage divide in the pin TS, you change the resistor, it will change the voltage in the pin TS, but both two ways(short to GND or add a big resistor) can not change the thermal shutdown, just like you mention the 154C.

    Best Regards,

    Kuno.

  • 0 in reply to Kuno Wu
    Intellectual 275 points

    Thanks Kuno!

    You are the best!