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UCC28251: Power management forum

古不菓莱
Prodigy 20 points
Part Number: UCC28251

How to use secondary side control with UCC28251?

what is it meaning?

Is it controlling the secondary PWM duty cycle and make primary following the secondary ?

  • 0
    TI__Mastermind 32995 points

    Hi

    Secondary side control means the PWM controller is located on the output side of the isolation boundary (secondary-side). Having the controller located on the secondary side brings many benefits such as: (1) Direct communication with the output load means the CC or CV feedback is directly sensed by the PWM (no opto feedback required) (2) If synchronous rectifiers are used, they can be driven directly from the PWM controller. easy to adjust the delay timing when the PWM controller is on the secondary side. (3) Direct digital communication with the load is easy because there is no isolation barrier between the PWM and micro-controller. The challenges with secondary side control are that the primary PWM signal must be transferred across the isolation barrier through gate drive transformers (or equivalent isolated gate drive) but in many cases, gate drive transformers are required for high-side drive even with primary side control. (2) the PWM on the secondary side must have a method for initial start-up. A dedicated secondary side bias supply must be available for start up.

    Regards,

    Steve M

  • 0 in reply to Steven Mappus1
    Prodigy 20 points

    thank you for your answer.

    I want to use the secondary side control, but the input UVLO, REM, and primary side control need the chip on primary side.

    do you have some case to solve the problem. primary side is high voltage with 400V, do you know some chip used as gate driver (high voltage and 1500Vac isolated)?

  • 0 in reply to 古不菓莱
    TI__Mastermind 32995 points

    Hi,

    TI has a complete portfolio of single and dual isolated, high voltage gate drivers. As long as you have a way to provide (>UVLO_ON) bias to the secondary side, you should have no problem using UCC28251 in a secondary side control application.

    Steve M