LM5036: 48V to 12V@0.5A Isolated Converter

Austin Allen

Part Number: LM5036
Other Parts Discussed in Thread: PMP10572, UCC2803

Hello team,

My customer is looking for a low cost, small footprint 48V to 12V@0.5A isolated converter. Shouldn't need more than about 6W. This converter provides power to MCU and CAN driver.

I am deciding between recommending Flybuck and Flyback. The "choosing the best topology" document seems to suggest that for this power level Flybuck would be the most appropriate. I saw that the LM5036 has a built-in Flybuck converter. Would this be a good choice?

Other reference designs I found close to required power level:

PMP8803.1 - Class 3 Low cost 12V/1A Flyback converter for PoE

PMP10572 - Class 3 Isolated Fly-Buck Power Module for PoE

PMP40589.1 - 2W aux power supply for single IGBT driver

Any suggestions or direction is appreciated!

Thanks

Austin

over 2 years ago

0 Sean Xu over 2 years ago

TI__Genius 14580 points

Hi, Austin,

PMP10572 is good reference design for your application. Flybuck has higher efficiency if you don't need isolation.

LM5036 has integrated flybuck, but it doesn't provide 6W for your application. It is too expensive for you, too.

Regards,

Sean

0 Austin Allen over 2 years ago in reply to Sean Xu

TI__Intellectual 2260 points

Hey Sean,

I actually do need isolation, but it looks like the Flybuck design is isolated? Is this still a good choice?

Thanks,

Austin

0 Sean Xu over 2 years ago in reply to Austin Allen

TI__Genius 14580 points

Hi, Austin,

If it needs isolation, low cost solution could be a flyback converter using UCC2803 as a controller.

Regards,

Sean

0 Austin Allen over 2 years ago in reply to Sean Xu

TI__Intellectual 2260 points

Hey Sean,

I think I'm confused, is this Fly-Buck architecture not isolated? It talks about opto-couplers and primary side regulation

0 Sean Xu over 2 years ago in reply to Austin Allen

TI__Genius 14580 points

Hi, Austin,

Fly-buck uses a coupled inductor. Primary side is a buck converter, and the secondary side is flyback. The flyback just handles small output power. Normally, it doesn't need feedback. The feedback comes from the primary side and buck.

Regards,

Sean

0 Austin Allen over 2 years ago in reply to Sean Xu

TI__Intellectual 2260 points

Hey Sean,

Can I assume 6W counts as small output power? As in this design can provide an isolated 6W output through the flyback?

Best

0 Sean Xu over 2 years ago in reply to Austin Allen

TI__Genius 14580 points

If you want to use LM5036 to get 6W from flyback, I doubt it. But if you want to use a separate flyback, there is no problem to get 6W.

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LM5036: 48V to 12V@0.5A Isolated Converter