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MOSFET Failure in UCC28070 during startup

Sudheendra Varna
Prodigy 70 points
Other Parts Discussed in Thread: UCC28070

Hello,

We are Using UCC28070 for 2.5kW Front end PFC Power .Sometimes PFC boost MOSFET fails during start up at Low line (100V). Used Design calculator. Attached is the schematics for reference. The Max Duty Cycle is set to 96.6%.The MOSFET will fail whenever there is a continues disturbance in mains power Like Loose connection Power Socket, or arcing in the inpt plug etc. Under Normal ON/OFF it will not fail.

Note: Enable PFC is Not used in the applications.

2.5kW PFC.pdf

  • 0
    TI__Mastermind 34465 points
    Your schematic does not show the part numbers for Q1 and Q4 the main power MOSFETS but I suspect that these parts cannot handle the power dissipation during a fault condition or at low line voltage. Please re-evaluate the parts selected.
    Also the resistor on the current transformer is not shown so I cannot calculate the peak drain current.
    I recommend that you monitor the gate drive and drain current waveforms during this fault condition.
    Also I notice that you are using 100uH boost inductors.
    Can you re-run your calculation with a larger inductance value which will give you a lower peak current.
    You may be able to trade off the cost of larger inductors against the cost of inexpensive MOSFETS.
    Regards,
    John Griffin