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UCC28180: TIDA-00652,

Dinar Prabhu
Intellectual 460 points
Part Number: UCC28180
Other Parts Discussed in Thread: DRV10983, TIDA-00652

Hello

I have built Reference Buck converter from TIDA-00652, On stand by , when DRV10983  is in standby mode(  minimum load to No load ) C1 (4.7uF/450v) and U4 (STQ1NK60ZR-AP) heat up in around 60 sec to 85deg C in open air bench test. As soon as the DRV10983 turn on. both components cool down. Is this temperature increase in low load condition as per design or is something wrong with my board.I have all the components as per the BOM for the design.Shouldn't BiasHV line be used only to start the power supply and power the UCC28180D only on startup and later MAG ( aux winding)  should power the I.C.?

I have confirmed all the voltages at VCC, Vsense, and gate of U4 , all are in specification. even Output voltage is 23.95V, so the I.C does turn on and generate gate DRV frequency.

Thanks and Regards

Dinar

  • 0
    TI__Mastermind 34465 points
    Hello Dinar,
    At startup and in standby the low voltage bias supply VCC is being generated from the rectified high voltage (BIASHV node ) through U4 and so you can expect U4 to dissipate power and heat up.
    During normal operation VCC is being supplied by an auxiliary supply (MAG node) on the pfc inductor. This MAG supply will turn off U4 and you will find that U4 cools down.
    This is normal operation of the circuit
    Regards
    John
  • 0 in reply to John Griffin1
    Intellectual 460 points

    Thank you John for the explanation, But why does the capacitor heat up as well? Can I drop the power using resistive network instead of just single 1k resistor R1? also instead of 20K resistors R24 and R25 ,can I increase the values and despite power there?
    I am concern that prolonged standby mode may degrade the capacitor, and I am trying to control the temperature to 65 deg C. Can any other method be used to power the I.C.

    Regards
    Dinar