TPS2378: Why my TPS2378 SPD circuits doesn't work

silong wang

Prodigy 120 points

Part Number: TPS2378

Below is my schematic, please help to find out errors.

and another question, which is the 1st pin, the real picture seems different with datasheet.

Thanks.

over 7 years ago

0 Darwin Fernandez over 7 years ago

TI__Mastermind 40120 points

Hi Silong,

It looks like the VSS and RTN are shorted to GND. If this is the case, the PSE cannot successfully do detection and class. These pins should be separate like what is shown in the EVM.

For Pin 1, it is the top left of the line that goes across the IC.

0 silong wang over 7 years ago in reply to Darwin Fernandez

Prodigy 120 points

Thanks Fernandez,

Do you have some simple reference design, the circuit has no external DC input, only powered by PoE .

0 silong wang over 7 years ago in reply to silong wang

Prodigy 120 points

or, how should I do some minor modification to the circuit to meet Cisco PoE switch, such 3560.

0 Darwin Fernandez over 7 years ago in reply to silong wang

TI__Mastermind 40120 points

Hi Silong,

To modify your circuit, you will need remove the connection between VSS and the RTN ground. After you modify the circuit schematic, please let us know so we can review. Thanks!

0 silong wang over 7 years ago in reply to Darwin Fernandez

Prodigy 120 points

You're right, now it's ok, Thanks.

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TPS2378: Why my TPS2378 SPD circuits doesn't work