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Original question:

UCC28251: External synchronization and output parallel

UCC28251： Application circuit for external synchronization

user4657807
Prodigy 120 points
Part Number: UCC28251
Other Parts Discussed in Thread: UCC28070, , UCC29002

Good morning!

I use 2 UCC28251 to design two DC/DC converters. The outputs of the two converters are connected in parallel. Use an MCU to provide external synchronization to UCC28251. Because I see there is only one common voltage loop in Figure 18 in the UCC28070 datasheet. Therefore, do PINs such as VSENSE, OVP, REF, FB, COMP, SS, SP, PS in UCC28251 only need a common voltage loop or are they independent voltage loops?

  • 0
    TI__Mastermind 32775 points

    Hi

    When you parallel converter outputs, you need to consider output current sharing, fault protection, fault recovery, etc. Two independent converters need to each be compensated, controlled and regulated independently first. You can synchronize the two UCC28251 converters from the MCU (F<1.8 MHz) as you described but you still have the problem of current sharing. Take a look at SLUP207 and the UCC39002 load share controller. Also see PMP8906, which uses the UCC29002 to parallel two flyback converters.

    Regards,

    Steve M