UCC28710: Used in a flyback circuit with multiple outputs

Derui Kong

Part Number: UCC28710
Other Parts Discussed in Thread: PMP4378, TIDA-00618

Hello,

I am using the UCC28710 to design a flyback circuit with multiple outputs and there are several questions that confuse me.(The designed circuit is shown in Figure).

The first question is whether the UCC28710 can support multiple output flyback circuits？
the second question is whether a synchronous rectifier can be used on the output side, and if so, will the ripple caused by the synchronous rectifier MOSFET affect the voltage sampling on the Vs pin of UCC28710?

Best Regards，

Derui Kong

over 1 year ago

+1 Harish Ramakrishnan5 over 1 year ago

TI__Mastermind 19435 points

Hi Derui,

Thank you for the query on UCC28710.

1. Yes it can support multiple outputs. Please refer PMP4378 (with SR) and TIDA-00618 for multi output flyback reference designs.

2. In multi output flyback designs, the difficulty for the PSR controller is that it needs to determine when the most heavily loaded diode has ceased conducting. The sampler within the controller needs to detect the knee point exactly to ensure this happens. If the voltage is sampled at the wrong time there will be output an voltage error that changes with load. The following article shows how this can be done reliably in multioutput designs.

https://e2e.ti.com/blogs_/b/powerhouse/posts/designing-multiple-output-converters-with-primary-side-sensing

Please let us know if you have questions.

Regards,

Harish

0 Derui Kong over 1 year ago in reply to Harish Ramakrishnan5

Prodigy 20 points

Many thanks for your warm help!

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UCC28710: Used in a flyback circuit with multiple outputs