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UCC28180: UCC28180 OCP

Alvin Francisco
Prodigy 190 points
Part Number: UCC28180

Hello,

is the computation for the peak current limit for low line and high line input voltage? Thanks

Regards,

Alvin

  • 0
    TI__Mastermind 27095 points
    Hi Alvin,

    Thanks for your interest in UCC28180. During steady state operation, the maximum peak inductor current in a boost topology occurs at minimum input voltage. For a PFC boost design that supports both low line and high line operation, you will want to size your sense resistor based on your expected peak current at low line.

    If the sense resistance is calculated using the peak inductor current at high line operation, the converter would trip the overcurrent threshold when trying to operate at low line.

    Best Regards,
    Ben Lough
  • 0 in reply to Benjamin Lough
    Prodigy 190 points
    Hello Benjamin,

    Will the PCL of UCC28180 limit the Inrush current at low line? Thak you for answering my question.

    Regards,
    Alvin
  • 0 in reply to Alvin Francisco
    TI__Mastermind 27095 points
    Hi Alvin,

    The PCL is meant more for cases where the PFC is loaded beyond its intended max output power.

    To limit inrush, I would suggest using an NTC to limit the inrush current and a bypass diode connected from the diode bridge to the output. The NTC resistance will be large at first since it is cold and as you begin switching, the NTC heats up and the resistance of the NTC falls. The bypass diode will prevent the large inrush current from saturating the inductor and is only forward biased during startup when the output voltage is less than the rectified input.

    This method for limiting inrush is also used on the UCC28180EVM (RT1 and D2):www.ti.com/.../sluuat3b.pdf

    Best Regards,
    Ben Lough
  • 0 in reply to Benjamin Lough
    Prodigy 190 points
    Hi Benjamin,

    Thank you sir! you are of big help.

    Regards,
    Alvin