TPS2375: 12V/6W Reference Design

Mike McDonald

Part Number: TPS2375
Other Parts Discussed in Thread: PMP20531, PMP30290, TPS2373-4EVM-758

Hi, the PMP5595 reference design seems have the ideal characteristics to power our PoE application. I am noticing in the schematic that the the connections to the transformer (T1) is different then some of the other reference designs.. e.g. PMP20531, PMP30290. Can anyone confirm that the configuration shown is correct? I want to connect the TD+/- and RD+/- pairs to our ethernet PHYS which is on the isolated side.

Thanks.

mike

over 6 years ago

0 Darwin Fernandez over 6 years ago

TI__Mastermind 40650 points

Hi Mike,

This is currently being looked into and an answer will be posted when available. Thanks!

0 Thomas Amlee over 6 years ago in reply to Darwin Fernandez

TI__Genius 9230 points

Hi Mike,

Thanks for pointing that out! The connection for the transformer on PMP5595 is CORRECT. For PMP20531 & PMP30290, T1 is basically mounted upside down. This is being corrected in future designs.

PoE takes the DC power off the cable side of the transformer which has the internal common mode choke. This inherently protects the data side from EMI generated by the switching power supply on the PoE side.

Thanks,
Tom

0 Mike McDonald over 6 years ago in reply to Thomas Amlee

Prodigy 140 points

Thanks for the clarification, my research also indicates it's preferable to have the common mode choke on the line side. I notice on most designs the centre taps on the data port side are brought out and decoupled with something like 0.1uF, I am not seeing this on thr PMP5595, any comment on this?

Thanks.

0 Thomas Amlee over 6 years ago in reply to Mike McDonald

TI__Genius 9230 points

Typically, we terminate the data side similar to how it is configured on the TPS2373-4EVM-758 design, but some designs do not have data side termination. The data side termination is defined by what is recommended for the chosen ethernet PHY/microcontroller used. Our focus is purely PoE.

0 Mike McDonald over 6 years ago in reply to Thomas Amlee

Prodigy 140 points

ok thanks

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TPS2375: 12V/6W Reference Design