UC2827-1： The buck side SR controller.

Chun Hung Chen

Intellectual 590 points

Part Number: UC2827-1
Other Parts Discussed in Thread: UCC24612, UCC24610, UCC24624

Hi TI Team

I'd like to design a 20A current fed push-pull (CCM).

I think I need a SR controller and the mosfet to reduce the PD of the low side current loop of buck converter.

So, do you have any advice?

Thanks

over 4 years ago

0 Colin Gillmor over 4 years ago

TI__Mastermind 25570 points

Hello Chun

The first question is what is the output voltage of your PSU. Then check whether the gains in efficiency you get from an SR are worth the added complexity. Anyhow, TI offers a selection of SR controllers

UCC24610, UCC24612, UCC24624. Here's a link to the product selection table where I got these device numbers.

http://www.ti.com/power-management/offline-isolated-dcdc-controllers-converters/synchronous-rectifier-sr-controllers/products.html#p749=4.4/4.2;4.5/4

Please let us know if you need any further help.

Regards

Colin

0 Chun Hung Chen over 4 years ago in reply to Colin Gillmor

Intellectual 590 points

Hi Colin

The first question is what is the output voltage of your PSU.

This a step down buck converter, 48V in and through T to 300V out.

Thank you for your information.

0 Colin Gillmor over 4 years ago in reply to Chun Hung Chen

TI__Mastermind 25570 points

Hello Chun

Thanks for the information - At 300V out the choice of SR or diode would go something like this

Diode Vf - 0.8V, Maybe more because high voltage ultra-fast Si diodes have a high Vf. At 20A this is 16W loss. Split between two devices - one for each end of the centre tapped secondary - so you would lose 8W in each. 16W loss from 6kW is 0.25% drop in efficiency.

SRs, Assume 0.25m Ohm parts, loss is 7W in each - the Rds on is normally quoted at 25C so you would need 20mOhm parts. The efficiency loss would be 0.23%. Virtually the same as with diodes.

Regards

Colin

0 Chun Hung Chen over 4 years ago in reply to Colin Gillmor

Intellectual 590 points

Super professional

I will use the SR on the Buck side and use the diode in push-pull transformer secondary.

Thank you.

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UC2827-1： The buck side SR controller.