TPS2378: TPS2378 PoE and PSE SWITCH identification problems

Hi Tom,

I am currently looking into this. I will post an answer within 24hr or sooner when available. Thanks!

Dear Sir,

Because our customers are waiting for answers and solutions to this question, we need your help. Thank you very much

Hi Tom,

Looking at the post, I don't see a specific question about the issue? A PoE PD should be able to do hardware classification and LLDP. Per the standard a PoE PSE can choose to do either LLDP or hardware classification, therefore a PD end equipment should do both. Part of the PD end equipment is the PD controller itself (TPS2378). A PD controller can only do hardware classification while a LLDP must be done at a system level (with a microcontroller on the PD load). Does your customer have a microcontroller that can negotiate higher power to the PSE through the data lines?

So a PSE that does LLDP will send a single class finger first, then the PD will power up to 13W, then if the PD wants higher power, the microcontroller on the PD load will negotiate with the microcontroller on the PSE for 25W, then if the PSE can deliver higher power, it will send it, then the PD can go to higher power.

Hi Darwin,

For this issue, we only get the following information from customer feedback, and there is currently no detailed analysis of the issue.

Questions:

1.Does the TPS2378 support LLDP? (Our Ccstomers mentioned that LLDP is not working properly)

2.How to gradually clarify and solve the problem?

Test device:

1. POE PD: ED004 is our company product that POE AMP with DANTE function and PoE chip use TPS2378

2. LAN Switch: Cisco Catalyst Series PoE+ switch

   ED004 when using a Cisco Catalyst Series PoE+ switch, the switch did not recognize the amp as a PoE+ device so the switch port would only deliver 15W. You can see on the attached picture the device does recognize the amp as a Class 4 device but it needed command to the switch to activate the PoE+ portion. This device will need to implement LLDP for POE+ power management.

Thanks  a lot.

Hi Tom,

1. There is no PD controller in the industry that does LLDP. This is because LLDP is not hardware based but software based. So the microcontroller on the PD load should be implementing LLDP.

2. Does your system have a microcontroller that can negotiate through the ethernet data lines to the PSE? This will be needed to solve the issue. Otherwise the PSE will always turn On to 13W first. 

Otherwise, can you configure the PSE switch to only do hardware classification? I've seen many PSE switches with this capability.