UCC25600: How ucc25600 handle large gain?

Fu Fleming

Prodigy 140 points

Part Number: UCC25600

Ucc25600 frequency range is 40~350KHz, if the LLC gain range is larger and out of the frequency limitation.

How can we handle it? Can we induce PWM or burst mode for the IC in such condition?

Thanks

over 4 years ago

0 Pye Naing over 4 years ago

TI__Prodigy 590 points

Hello, your thread has been assigned. You should receive a reply shortly.

0 Fu Fleming over 4 years ago in reply to Pye Naing

Prodigy 140 points

Thanks. Waiting for the reply for my case.

0 Yunsheng Qu over 4 years ago in reply to Fu Fleming

TI__Genius 9790 points

Hi, poster

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

0 Fu Fleming over 4 years ago in reply to Yunsheng Qu

Prodigy 140 points

Then you mean that the IC can get larger gain range? For example, if the gain is from 5 to 0.2, when the gain is 10 the frequency is 40K; when the gain is 0.8, the frequency is 350K. From you description, the gain can be achieved to 0.2( in this case the required frequency is larger than 350K, e.g. 500K), but the IC will disable the driver for a while(burst mode).

Is my understanding right?