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UCC28061: UCC28061 single phase operation question

Red Yen
Expert 4340 points
Part Number: UCC28061
Other Parts Discussed in Thread: UCC28064A

Hi Support team 


In order to control PHB into single phase stage, the COMP voltage is key factor, 

what conditions that will affect the COMP voltage (VINAC? TEST? VSENSE? Choke parameters other) and how to well control the single / dual phase in different AC input & output loading?

  • 0
    TI__Mastermind 26725 points

    Hi Red,

    According to datasheet, UCC28061 looks at the voltage on the PHB pin and compares to an internal 800mV reference to determine whether to operate in single phase mode or interleaved mode. If PHB is connected to COMP, the converter will fall into single phase mode whenever COMP becomes less than 800mV. Ideally, COMP should be a flat voltage whose magnitude represents power demand. My suggestion would be to have a low bandwidth to avoid twice line frequency ripple from creating ripple on the COMP voltage. COMP responds to what it sees on VSENSE so keeping the VSENSE signal clean is important. Because this is closed loop, the power stage will also affect the behavior of COMP. Because TSET and VINAC affect the on time, these will have an indirect impact on the behavior on COMP. The power stage, VINAC and TSET are normally selected based on the required power output and AC input range.so there is not much room to deviate with these parameters. 

    If your customer is open to using UCC28064A, this controller has an adjustable threshold for the single phase mode/interleaved mode transition and would offer more flexibility.

    Best Regards,

    Ben Lough