TPS23753 - cannot get more than a few mA

giro360

Other Parts Discussed in Thread: TPS23753

Hi,

We have designed a board based on TPS23753 to supply 12V output.

The design is attached 2086.design.pdf - we compared it with several reference design and cannot find what is wrong with our design.

When using the POE12V output to power an other board, we found out that we cannot get more than 32 mA output, where we need at least 500mA.

Can anyone have a quick look at the attached schematic 2086.design.pdf to see if something is wong ?

Thanks a lot

Ric

over 12 years ago

0 Eric Wright over 12 years ago

TI__Mastermind 42795 points

I do not see anything obviously wrong with the schematic. Are you sure that what is on the schematic matches what is on the actual board? R57 seems a bit small (try removing this for starters). We don't know what the specs are for T2 (vendor PN for a similar TI design is Coilcraft POE70P-12L).

Capture some waveforms at U5-3,4,5 as well as POE12V during the failure.

0 giro360 over 12 years ago in reply to Eric Wright

Prodigy 160 points

Hi Eric,

Thank you for the quick reply.

T2 is Wurth Electronic 749119333

We just removed R57 but it did not change anything.

Any other idea ? I don't have any way here to capture some waveforms unfortunatly :(

Thanks

Richard

0 Eric Wright over 12 years ago in reply to giro360

TI__Mastermind 42795 points

This transformer is designed for 3.3V output applications. You probably need something like the 750311439 which has the proper turns ratio for this application.

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TPS23753 - cannot get more than a few mA