TPS23730: TPS23730_PSR topology with Driven Synchronous Flyback design

Ching-Fei Ho

Part Number: TPS23730
Other Parts Discussed in Thread: PMP22477, TPS23731EVM-095

Tool/software:

Hi Team,

I have a project that need to use TPS23730 which support 802.3 bt with 51W (12Vout), there would be both input power of ethernet network port and 48VDC adapter.
We would like to use PSR topology with Driven Synchronous Flyback, does pin41(GAT2) just connect to pulse transformer which drive the secondary mosfet?
Does TPS23730 have this kind of reference design that I could take reference?

And what is the function for below circuit that in PMP22477 reference design?

Thanks.

28 days ago

0 Diang Xing 27 days ago

TI__Mastermind 25161 points

Hi Ching-Fei,

Thanks for reaching out!

The sync FET is more commonly driven by a bias winding of the major flyback transformer with a lower cost (for using bias winding driving sync FET and using APD pin to set 48V adapter priority, you can check the schematic of TPS23731EVM, which is from the same family with TPS23730 at www.ti.com/.../TPS23731EVM-095). It can be driven by GAT2 + pulse transformer also but not common.

The circuit in page3 is for power limiting. It is also not common to use and you can delete it. Please find a version without power limiting circuit. TPS23730+Tele+PSR diode Flyback 12V_output Class6_Sch.pdf

Please let me know if you have other questions.

Best regards,

Diang

0 Ching-Fei Ho 26 days ago in reply to Diang Xing

Prodigy 110 points

Hi Diang,

Thanks for your feedback. Do you have a suggestion transformer of TPS23730(12VOUT/51W)?

I need to use the transformer as the type of LDT1038-50R in my TPS23730 design, because my design of secondary side is as same as the reference design of TPS23731EVM-095.

Thanks.

0 Raymond Lin 25 days ago in reply to Ching-Fei Ho

TI__Mastermind 27676 points

Hi Ching-Fei,

PoE team is currently out of office and will be back in Nov.12. Sorry for the delay.

Thanks and Regards,

Raymond Lin

0 Ching-Fei Ho 20 days ago in reply to Raymond Lin

Prodigy 110 points

Hi Team,

Do you have any update about the transformer of TPS23730(12VOUT/51W)?

I need to use the transformer as the type of LDT1038-50R in my TPS23730 design, because my design of secondary side is as same as the reference design of TPS23731EVM-095.

Thanks.

0 Diang Xing 19 days ago in reply to Ching-Fei Ho

TI__Mastermind 25161 points

Hi Ching-Fei,

LDT9055-51R and PL5112-003SR could be used for 12V Class-6. LDT9055-51R is 48W as listed but considering flyback efficiency is normally lower than 48/51 = 94.1% it is ok to use too.

LDT9055-51R.pdf PL5112-003SR spec.pdf

Best regards,

Diang

0 Ching-Fei Ho 19 days ago in reply to Diang Xing

Prodigy 110 points

Hi Diang,

My secondary design of TPS23730 (12VOUT/51W) would be as below capture( TPS23731EVM-095), the transformer of LDT9055-51R and PL5112-003SR that you suggest seems cannot use on this kind of secondary design.
Could you help suggest a suitable transformer for TPS23730?
Thanks.