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TPS26624-25EVM: Regarding absolute maximum operating temperature

Venugopal.S
Prodigy 230 points
Part Number: TPS26624-25EVM
Other Parts Discussed in Thread: TPS2662

Absolute maximum value of junction temperature is the same as the thermal shutdown temperature value T_TSD. Will this cause permanent damage to device or deteriorate its performance if the device is operated at thermal trip level for prolonged period of time ?

  • 0
    TI__Expert 8630 points
    It is not recommended to use device with junction temperature beyond TSD. There is internal thermal shutdown function which shuts down the device as junction temperature reaches TSD.
  • 0 in reply to Lokesh Ghulyani
    Prodigy 230 points
    Hi Lokesh,

    The internal thermal shutdown temperature is 155 degrees. During a fault, there is a chance that the IC goes to thermal shutdown, turns off the FET and retries after 512ms.

    Again in the next cycle, if the fault persists, it will reach thermal shutdown temperature and trip and turnoff the FET.

    This keeps repeating if my fault persists continuously.

    This means that the IC will reach the thermal shutdown temperature after every 500 ms and then trip.

    My question is, this thermal shutdown temperature is same as the absolute maximum temperature, as per the datasheet. I was expecting the absolute maximum temperature to be slightly higher than the shutdown temperature, just to be on the safer side.

    Now the absolute maximum temp is 155 degrees and my IC reaches 155 degrees on every cycle during a persistent fault, until the fault is corrected.
  • 0 in reply to Venugopal.S
    TI__Expert 8630 points

    Hello Venugopal,

    This is correct. But the as the device reaches TSD (155C) it shutsdown immediately. Due to thermal impedance of package, the junction temperature rises slowly with power dissipated by the device. For time taken by device to reach thermal shutdown temperature with different power dissipation, you can refer Figure 52 on Page 29 of the datasheet of TPS2662. 

    The device would remain at Thermal shutdown temperature for very short duration (few ms). There is delay period of 512ms between auto retires, so the junction temperature will come down significantly during this time and rise again when device turns on.