Digi Connect ME 9210 and Power Pass-Thru (VETH) pins

Question

On page 14 of the Digi Connect ME 9210 hardware reference document (90000897_K.PDF), the document describes the Ethernet Interface Pin Assignments. Pins 4, 5, 7, and 8, are defined for the EPWR functions used for IEEE 802.3af Power Over Ethernet (PoE) as is expected.

On page 11 of the same document, the Power and Device Interface Connector Pin Assignments are defined. Here, pins 1 and 2 are defined for the VETH power pass-thru function.

What is ambiguous to me is the internal relationship between the four power pins on the RJ-45 connector with respect to the two power pins on the 2x10 connector. Is there documentation available for this somewhere?

With a discrete IEEE 802.3af circuit implementation, the four power pins on the RJ-45 connector go through bridge rectifiers before interfacing with the rest of the PoE electronics and controller IC. Are these bridge rectifiers implemented in the Digi Connect ME 9210 module?

Answer 1

After additional research, I wish to revise/refine my request for assistance.

Based on the signal names near P1 on the schematic on page 67 of 90000897_K.PDF, the RJ-45 pins 4 and 5 are shorted together as POE_RJ45_4/5, and the RJ-45 pins 7 and 8 are shorted together as POE_RJ45_7/8.

With that said, somewhere in the PoE circuit there should also be POE_TX_CT and POE_RX_CT signals.

Do the Digi Connect ME 9210's VETH+ and VETH- pins correspond to the POE_TX_CT and POE_RX_CT signals, do the VETH+ and VETH- pins correspond to the POE_RJ45_4/5 and POE_RJ45_7/8 signals, or do VETH+ and VETH- pins correspond to the outputs of the bridge rectifiers, PVIN+ and PVIN- on the page 67 schematic?

I would be pleasantly surprised if the bridge rectifiers are included in the Digi Connect ME 9210 module. Given the small size of the module, maybe this is over-optimistic.

On the other hand, if the bridge rectifiers are NOT included in the Digi Connect ME 9210 module, I'm not sure how one goes about implementing a 802.11af compliant PoE design using the Digi Connect ME 9210.

Answer 2

Via the Digi "eService Portal" accessed via http://www.digi.com/support/eservice/index.jsp I have learned that the bridge rectifiers are included in the Digi Connect ME 9210 module.

In more detail:

There are two bridge rectifiers contained in the ME 9210 RJ45 Ethernet connector that support both mid and end span POE and the POE power is brought out of the ME 9210 on the user connector pins 1 and 2. The 9210 ME's POE connections are as shown in the attached schematic snapshot.

The "chip side" pins PWR+ (pin 5) and PWR- (pin 6) are brought out to the user connector pins 1 and 2. As you can see the mid and end span connections from the ethernet cable to be connected to the user pins by way of two diode bridges. This connector is only used for the 9210 ME's.