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UC2854B-EP: Startup delayed at 110deg ambient temperature

DSR
Prodigy 60 points
Part Number: UC2854B-EP
Other Parts Discussed in Thread: UC2854, UC1854

Hi

I am using UC2854 for 115V, 360Hz to 30V convertion for 15W power supply, For room temperature gate pulse starting at 2nd negative cycle itself, but while testing at 110deg the pulse starting at 3rd negative half cucle only. I am starting from zero deg phase only for all temperature. I need to meet 12ms startup time, I can't meet at high temperature due to this switching delay, In datasheet there is no information about this delay.

  • 0
    TI__Expert 3070 points

    Hi DSR,

     

    Thanks for considering TI products.

    UC2854 is recommended to operate between –40°C to 85°C only.

    Consider using UC1854.

    As part of debug, please observe the voltages at the following pins and compare them with at 25'C and 110'C.

    ENA, SS, VCC, VREF, VRMS, VAOUT, CAOUT. If no change is observed, please probe the other pins also and look for difference in operation. If you follow these steps, you should be able to find clues why there is an additional delay and be able to debug.


    Regards
    Hemanth