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UCC28180: UCC28180 no startup

Ioannis Manousakas
Prodigy 90 points
Part Number: UCC28180

Hi, 

I am working on a PFC stage using the UCC28180 as shown in the schematic but the IC does not startup...Any suggestions on what I am missing?

Thanks

  • 0
    TI__Mastermind 34465 points

    Hello ,

    You need a voltage of greater than 12V on J2 and a voltage of greater than 65V on J1 in order to get a gate drive signal to the MOSFET.

    Please make sure these voltages are present and that the circuit is wired as in the schematic

    Regards

    John

  • 0 in reply to John Griffin1
    Prodigy 90 points
    Hi John,

    I used Vcc=12V and rectified 110Vac for input but the output does not increase to higher than that.
    As there is no signal at the gate, I suspect that the IC never starts.
    The circuit was checked on breadboard and on PCB with the same results...

    Regards
    Ioannis
  • 0 in reply to Ioannis Manousakas
    TI__Mastermind 34465 points
    Hi Ioannis,
    I notice you only have 0.2uF on the pfc output
    Is this the total bus capacitance ?

    The only protective features that will keep the controller off are UVLO on VCC and open loop protection on VSENSE.
    Check with a multimeter that :
    VSENSE is greater than 0.88 v
    VCC is greater than 12.1 v

    Disconnect the MOSFET gate and check the gate drive with a scope or test at no load and you should measure about 380 Vdc

    Regards
    John
  • 0 in reply to John Griffin1
    Prodigy 90 points

    Hi John,

    Thanks for the information. I managed to better understand the controller start up!

    The bus capacitance is actually the C16=680uF.

    The controller needs the VSENSE and VCC as you mentioned and sometimes a small negative voltage at ISENSE for startup.

    I managed to have gate signal but only without the Vin... When the Vin was increased VSENSE increased and the controller started momentarily. Probable because the layout was not done as suggested in the datasheet, the controller was damaged...I will modify the layout and test it again.

    Thanks again for the help.

    Regards,

    Ioannis