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TIDA-00779: Module is failing while repeated turning on and off

Ijas Ahammed
Prodigy 50 points
Part Number: TIDA-00779
Other Parts Discussed in Thread: UCC28180

Tool/software:

We have developed a 3kW PFC using TIDA-00779 reference. The design is for a fixed 395V PFC circuit. Apart from reference design we have used a single SiC MOSFET MW65R048M1H and single boost diode as WNSC6D30650W6Q. We have loaded up to 3kW without any issues. (Thermal and other things are fine while continuously loading many hours)...

We will turn on the circuit with no load or a light load at different times for different tests. But the circuit fails at the turning on time at some instants. Our MOSFETs are getting fail at these instants. Diodes and other power components are safe. MOSFETs  Gate, Drain and Source all were getting shorted after failure. Input voltage is giving nominal 230Vac for tests.  Can you support us to identify the failure cause?

I am sharing my circuit along with this...

PFC_ckt1.pdf

  • +1
    TI__Intellectual 850 points

    Hi, Ijas

      I think this should be the power on sequence issues, since DCBUS capacitor C8/C10 is so big, it will keep 12V for a long time, so UCC28180 may still work for a long time even you remove AC input. Then you connect AC input again, so pls check:

    1. Check 12V after remove AC input under light load.

    2. Check output of UCC28180 after remove AC input, see if it still have output to drive MOSFET.

    2. Check if relay inrush protection circuit works well when you connect AC again.

    Regards

    Hely

  • 0 in reply to Hely Zhang
    Prodigy 50 points

    Thanks for your valuable support. We have debug the issue based on your suggestions. The inrush circuit with NTC bypass we modified with 10 Ohm 10W fusible resistor instead of 10 Ohm NTC. In some of power on off sequences the NTC will be heated and its resistance dropped much. So on the next power on it will not protect the circuit from inrush. This we resolved with a fixed resistor with higher wattage.