Other Parts Discussed in Thread: UC2825A
My power converter shuts down and draws very high current from its AUX supply. The UC2825A-EP draws about 50 mA at 10.5V at room temperature. When I increase the board temperature
above 85C and allow a several minute soak time, my AUX supply current limits (>500 mA) and the power converter shuts down for 10's of seconds then restarts for 10's of seconds. This cycle will repeat until I let the board cool down to about 70C where it will restart and stay running until I heat the board again above 85C.
There are other chips running off the AUX supply including an external gate driver. I cannot measure the UC2825A-EP Tj but with 0.5W dissipation, we can expect that we are close to the data sheet maximum 528 mW @ 85C.
Will the UC2825a-EP draw high current at elevated temperature then draw the nominal current when it cools down?
I could not find a description of the thermal shut down behavior of this device. Could you please describe what functions are disabled if there is a thermal shut down feature?