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Q: TPS54260 maximum temperature by 1090226
Hello,
I received the following question from a customer:
"In my design I'm using step-down converter TPS54260D. In datasheet I'm found information about maximal temperature of junction - 150 degrees C.
But also i found parameter "thermal shutdown at 182 degrees C". I calculate conduction loss, switching loss, gate drive loss - in sum P=0.07 W. Thermal resistanse of TPS54260D is Q=57 C/W, consequently I calculate maximal ambient temperature:
Ta = Tjmax - P*Q = 182 - 57*0.07 = 178 C.
It is device work at this temperature (178 C) or I make mistake? "
Can anyboday clarify the situation between the maximum junction temperature 150 degrees C and the thermal shutdown at 182 degrees C?
The device should never be operated above its maximum operating temperature rating of 150 C (the absolute maximum rating). Above this temperature, there are no guarantees of device operation. Most likely, the device will not fail immediately, but longer term reliability could be affected. The thermal shutdown should never be reached. In addition, we do not specify the tolerance on the thermal shutdown temperature.
A better way to do the calculation is to subtract the temperature rise in the IC from 150. Also note that the theta JA is only specified for the specific board described in note 1 beneath the package dissipation ratings. This app note, http://focus.ti.com/lit/an/slva397/slva397.pdf can be used to find the theta JA on the customer's board.