the customer use the auxiliary power to power supply, however, there is no output

dave lan

Part Number: TPS23756

HI sir，

Now customers are doing a AP project, using our TPS23756, there is a problem, the customer use the auxiliary power to power supply, however, there is no output, the output has been off the electricity, and connected to the transformer this a Mosfet hot, please help to analyze, the attachment is the schematic diagram, thank youpdm-15w v100.pdf

over 7 years ago

0 Thomas Amlee over 7 years ago

TI__Genius 9230 points

Hi Dave,

To clarify your question:
Your customer is unable to get an output (5V, 3A) when using auxiliary input & the primary side FET is getting very hot. Is this correct?

I can take a look at your schematic & get back to you next week.

Thanks,
Thomas A.

0 Thomas Amlee over 7 years ago in reply to Thomas Amlee

TI__Genius 9230 points

Hi Dave,

VDD and VDD1 need to be connected together so that the aux voltage input can power the PD controller through VDD.

For more info about PoE ORing options see this app note: http://www.ti.com/lit/an/slva306a/slva306a.pdf

Thanks,
Thomas A.

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the customer use the auxiliary power to power supply, however, there is no output