TPS2372: 12.5k Phihong detection

Daniel Campano

Part Number: TPS2372

Hi All,

I'm developing a PD with the TPS2372 and I have a doubt about Phihong 12.5K detection resistor. When a Phihong injector detects a 12.5k resistor, it delivers power through the 4 pairs, but it still does classification?.

When my PD is configured to be used by an IEEE802.3bt PSE it is set as Class 6 ( 24.9k detection) but when it is set to 12.5k detection resistor should it be set as class 4 or class 6?, or it is irrelevant as CLSA is 63.4ohm for Class 4 and Class 6 anyway?. I have a switch to change from 24.9K detection to 12.5k and I don't know if I should use to change from 24.9k and Class 6 to 12.5k and Class 4.

Thanks,

Winsu

over 6 years ago

0 Daniel Campano over 6 years ago

Intellectual 470 points

It could be the case that it doesn't do classification once it has detected a 12.5k detection resistor and it just delivers power through the 4 pairs?. That would mean that classification resistors are completely irrelevant if 12.5k resistor is detected, is this correct?.

0 Darwin Fernandez over 6 years ago in reply to Daniel Campano

TI__Mastermind 41770 points

Hi Daniel,

That is correct, the non-standard Phihong injectors I have tested in the past will output full power (4 pair) when a 12.5k ohm is detected. It is independent of Class resistance.

Regards,
Darwin

Power management

Power management forum

TPS2372: 12.5k Phihong detection