TPS2372-4EVM-006: TPS2372-4EVM-006

Daniel Campano

Hi All,

I'm testing the TPS2372-4EVM-006 set at Class 6 with an application which takes 41.5w. I have used a BT injector to power up the TPS2372-4EVM-006 and the 41.5w application with a 100m Cat 5 cable. In order to do the test I need to set previously my application at full power ( 41.5w), then power everything up and verify if it is able to do the handshake and power up the application at full power with 100m cable. I have done it numerous times and I have seen my application collapse twice ( the rest of the times it performed fine). I don't understand why it has collapsed as the PD has a wattage budget of 51W ( which is not exceeded) and the PSE should be able to exceed the 51W for cable losses.

The IEEE802.3bt standard states that the maximum wattage at the application is 71.3w ( class 8) and 18.7w for cable loses ( as the total is 90w).

How much wattage can we lose when the PD is set to 51w and the injector is an IEEE802.3bt compliant?.

Any idea why it collapsed?.

Thanks,

Daniel.

over 6 years ago

0 Thomas Amlee over 6 years ago

TI__Genius 9230 points

Hi Daniel,

By collapse, are you saying that it is failing to power up or is it able to power up, then removing power during operation?

Regards,
Tom Amlee
PoE PD Apps Engineer

0 Daniel Campano over 6 years ago in reply to Thomas Amlee

Intellectual 470 points

Hi Thomas,

By collapse I mean that it didn't power up the PD and application at all. I did see the TPH,TPL and BT leds blinking very quick. Most of the times it powered up the BT PD and application, and full power was available.

Regards,

Daniel.

0 Thomas Amlee over 6 years ago in reply to Daniel Campano

TI__Genius 9230 points

HI Daniel,

Be sure that the load is not attached during inrush. Could you try powering on without load, then attaching it?

Thanks,
Tom Amlee
PoE PD Apps Engineer

0 Daniel Campano over 6 years ago in reply to Thomas Amlee

Intellectual 470 points

Hi Thomas,

I'm using power good to control the application when it can pull current. I have tried several times with load and no load, and It is working fine. I'm starting to think that it was a bad connection on the RJ45( application).

Regards,

Daniel.

0 Thomas Amlee over 6 years ago in reply to Daniel Campano

TI__Genius 9230 points

Hi Daniel,

If you feel the issue have been resolved, could you click on the green "resolved" button on the post that you found most helpful? This could be your own post since you found the cable issue. It would help me close out this thread on my end.

If continued support is needed, feel free to reply with any additional questions or comments.

Thanks,
Tom Amlee
PoE PD Apps Engineer

Power management

Power management forum

TPS2372-4EVM-006: TPS2372-4EVM-006