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TPS7A47-Q1: Thermal shutdown temperature point design

Kai Lai
Expert 5846 points
Part Number: TPS7A47-Q1

Hi Team,

My customer use TPS7A47-Q1 in his automotive project.

He use it in a 10Vin / 9Vout 500mA Max. load design.

Now he had a output keep short to GND test, need to make sure our device safety include the thermal perform.

He found that when he short Vout to GND, our TPS7A47-Q1 will enter a restart period, I assume that since the Thermal Protection.
But during the on/off period, the measure temp. on the IC case is about the 130C, it is over the Tj recommend range, this scenario will have risk right ?

Customer is wondering about taht our Tj recommend range is up to 125C, but why we set the thermal protect point at 150~ 170C?

Since even protect IC at Tj 170C that had been over 125C a lot, it could already have had a bad effect on IC ?

Thanks!

Kai

  • 0
    TI__Genius 12040 points

    Hello Kai,

                    For this device the Max recommended operating temperature is 145˚C (not 125˚C). It is good convention to have ~20˚C of hysteresis between shutdown and reset to prevent false shutdowns. To ensure long term reliability of the device it is best to operate the device such that the junction temperature is within -40˚C & 145˚C. Thanks!

    Regards,

    Srikanth  

  • 0 in reply to Srikanth Lolla Venkata
    TI__Expert 5846 points

    Hi Srikanth,

    Sorry I have a mistake here, my customer is using -Q1 grade solution, and -Q1 Max recommended operating temperature is 145˚C (not 125˚C).
    So now, he can accept is in-Q1 the thermal protect point is 150~170C.

    But if in non-Q1 part, they are still wondering to know why the Tj recommend range is up to 125C, but why we set the thermal protect point at 150~ 170C?

    Thanks! 

    Kai

  • +1 in reply to Kai Lai
    TI__Genius 12040 points

    Hello Kai,

                   It is typical to provide this margin of 25ºC (Max Recommended TJ:125ºC vs Thermal shutdown Temp :150ºC) to ensure that the part does not very often go into thermal shutdown when operated high ambient/junction temperatures. There is no other specific reason as to why this specific margin (25ºC) was provided for this part. Thanks!

    Regards,

    Srikanth

  • 0 in reply to Srikanth Lolla Venkata
    TI__Expert 5846 points

    Thank you, Srikanth.