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UCC25600: How ucc25600 handle large gain?

Part Number: UCC25600

The UCC25600 frequency range is 40~350KHz, then how about startup? it fixed at 350KHz?

Also if the LLC gain range is too large, the frequency limitation is not enough. But in the chip, PWM or burst mode is not available.

Then how can we handle this condtion by the chip?

  • Hello,

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  • Hi, fleming

    There is burst mode in the chip, there is no PWM mode in the chip. here is the explanation. 

    40kHz is the minimum switching frequency capability, you can program minimum switching frequency higher than 40kHz, but you cannot program minimum switching frequency lower than 40kHz. 

    Same as 350kHz as maximum switching frequency capability, When the control loop demands switching frequency higher than 350 kHz, the gate driver is disabled and the power stage stops switching. When the output voltage drops, the control loop begins to demand switching frequency less than 330 kHz, the gate driver recovers and the power stage begins to deliver power again. This allows the output voltage to be regulated. This burst mode can be easily disabled by limiting the maximum switching frequency to less than 350 kHz. In this way, the control loop will never demand a switching frequency higher than 350 kHz and burst mode operation will not occur.

    Yunsheng