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Original question:

CCS/UCD3138: UCD3138LLCEVM Debug Issue

UCC28056: Drive waveform abnormal & 90V input IC not work

Gabriel Wang1
Genius 4725 points
Part Number: UCC28056

Dear Expert

Input 90V ,ourput 20V ,3A-5A .bus voltage up to 370V

Customer change their mosfet Q2 to ON FCMT199N60 ,  their drive wavefrom become abnormal .

then they change the drive resistence ,drive wavefrom become normal ,but they found input 90V , 3A output transfer to 5A ourput ,PFC IC not work .bus voltage reduce to 160V RMS .

ON-FCMT199N60.pdf  ,

Schemetic:

Could you help to give some advice about this ? Many thanks

  • 0
    TI__Genius 9140 points

    hello Gabriel,

    can you clarify the "abnormal" and "normal " gate waveform? does the attached gate dirver waveform an" abnormal" waveform?

    please help to offer more information like:

    1.original mosfet part number

    2.abnormal waveform

    3.the mosfet being changed(you already offered)

    4:normal waveform

    5.Original driving resistor

    6.the resistor used that make the waveform normal

    for your second question, can you also clarify whether at this condition when output changes from 3A to 5A PFC is trying to boost the PFC voltage from 90V*1.414 to a regulated voltage like 350V or 390Vdc?

  • 0 in reply to David Huang33
    Genius 4725 points

    Dear David

    1.original mosfet part number

    OSS60R190JF ，Oriental-OSS60R190JF.pdf

    2.abnormal waveform

    CH1：Vcc CH2:Vgs

    3.the mosfet being changed(you already offered)

    4:normal waveform

    CH2 Vgs

    5.Original driving resistor

    150Ω

    6.the resistor used that make the waveform normal

    150 Ohm in parallel 10 Ohm

    7、for your second question, can you also clarify whether at this condition when output changes from 3A to 5A PFC is trying to boost the PFC voltage from 90V*1.414 to a regulated voltage like 350V or 390Vdc?

    90-132V AC input, PFC maximum capacitance is 250V,.180-240V AC input,PFC maximum capacitance is 370V.

  • 0 in reply to Gabriel Wang1
    TI__Genius 9140 points

    hello Gabriel,

    thanks for your information.

     please confirm with customer whether the PFC controller is trying to restart once 1 second ?

    if yes, the controller should be triggering the OCP2 protection.

    With less driving resistor allows the VGS much quickly to rise to the miler platform of the mosfet and pull the VDS to fall.

    in the datasheet, Tocp2Blk=250ns. So we need a smaller QG mosfet or a smaller turning on resistor to avoid the mis-triggering the ocp2 during this blanking time.

    this should be the cause.