TPS23754 don't have output

Chen Tao1

Intellectual 410 points

Other Parts Discussed in Thread: TPS23754EVM-383

Hi,

I copied TPS23754EVM-383 design. But there is no output.

PSE is always in class step.

Can you suggest which part is wrong?

Attached is sch.poe-ti-v0d9.pdf

over 9 years ago

0 Darwin Fernandez over 9 years ago

TI__Mastermind 41780 points

Hi Chen,

One thing I noticed about the schematic is that the input filter of the converter is not connected to primary ground. I wonder if after classification the converter tries to turn on but can't and so the PSE shuts off. Please confirm.

It may be good to take an EVM and compare the boards and make sure connections and board impedances are the same. It may narrow down where on the board could be the issue.

0 Chen Tao1 over 9 years ago in reply to Darwin Fernandez

Intellectual 410 points

Hi, Darwin,

Which filter do you mention about?
I don't have EVM on hand. So i can't compare the difference.

0 Darwin Fernandez over 9 years ago in reply to Chen Tao1

TI__Mastermind 41780 points

Hi Chen,

C16/17/18/20/21 should all be referenced to primary ground. In the schematic, it looks like they are floating.

Power management

Power management forum

TPS23754 don't have output