PMP23287: Reverse current protection when 24V is on output, but no VIN

BrandonAzbell

Part Number: PMP23287
Other Parts Discussed in Thread: TPS23730, LM5156

Tool/software:

For the PMP23287, using the Active Clamp Forward controller inside the TPS23730, does this circuit have any issue with 24V being present on the output but the TPS23730 disabled via the APD input?

A customer will have a separate power converter stage for the auxiliary input but needs to maintain isolation between the PoE path and this auxiliary path.

PMP23287 uses self-driving synchronous rectification to deliver 24V @ 2.5A.

Will this have issues with no switching from the TPS23730 but with 24V present on the output?

30 days ago

0 Darwin Fernandez 29 days ago

TI__Mastermind 41760 points

Hi Brandon, by issue do you mean since APD is HIGH and 24V is on the output, if there would be an issue with interoperability at the poe input?

0 BrandonAzbell 29 days ago in reply to Darwin Fernandez

TI__Guru 64470 points

See below image.

If power is available at the AUX (auxiliary power) input, it will assert APD on TPS23730 to turn it off and through the internal pass MOSFET, will disconnect the TPS23730. However, the MOSFETs of the primary side of the ACF transformer are still there, the synchronous rectifier MOSFETs (self driving) are potentially going to see the 24V.

Will this cause an issue?
Will the LM5156 SEPIC stage see a "load" caused by the ACF portion from the TPS23720?

0 Darwin Fernandez 28 days ago in reply to BrandonAzbell

TI__Mastermind 41760 points

Hi Brandon, i have looped us into a conversation with the product line. thanks!

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PMP23287: Reverse current protection when 24V is on output, but no VIN