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Original question:

TPS25926: TPS259261: Input transition rate at EN/UVLO pin

TPS25926: TPS259261 no output with high ambient temp

Lenna Yan
Intellectual 1960 points
Part Number: TPS25926


Hi Expert,

The customer uses TPS259261 on their design and found there is no output when putting the board in high ambient temp condition(up to 70℃). The normal operation current is 2A, and the voltage is 12V. Please see the test steps as below. I see there's temp protection inside the device and the threshold is 150℃. While power on the device, it should not be able to achieve such high temp immediately. Could you help analyze what may be the root cause? 

  1. Putting the board to the incubator and setting the temp to 70℃
  2. Power on the board after the temp reaching 70℃
  3. TPS259261 has no output
  4.  Setting the ambient temp a little lower, like 68℃, the output can start up successfully

  • 0
    TI__Guru 57737 points

    Hi Lenna,

    Startup into capacitive load is a stressfull condition for the internal FET. There would be significant power loss in the device as during startup there is voltage difference across the FET and current flow through it.

    You can try doing the following to avoid turn off of efuse at high temperatures.

    • Increase Cdvdt
    • Reduce Output capacitance
    • Make sure there is no load during startup. If there is load during startup, this adds to the additional power loss in the system.
    • Improve the Layout to reduce the RQJA of the efuse