Power over Ethernet (PoE) PSE-KIT Project

PoE (Power over Ethernet) is a convenient feature that allows devices to receive power through Ethernet UTP cables.

That's why countless devices support PoE, and many makers have also created projects using PoE. However, most PoE-related projects made by makers are limited to Powered Devices (PDs).

Why is that...? Because PoE-PDs, which receive power, are simpler and have fewer considerations than Power Sourcing Equipment (PSEs) that supply power!

I thought that if we could monitor and control the voltage, current, temperature, and status of each port on a PSE—including the ability to turn them on/off—it would enable more efficient power management in smart systems. So, I decided to create a PSE-KIT.

System Block Diagram

The overall system block diagram is as follows.

Initially, I considered converting 220 VAC to 54 VDC, but after learning that PoE-specific 54 V adapters are widely available on the market, I changed the power input to 54 VDC. (The fact that I lack AC to DC design skills also played a part.)

Component Selection

Voltage Conversion

For converting 54 V to 3.3 V and 54 V to 5 V, I used Torex's XC9702A75CDR-G.

Reason for Selection: It has a maximum input voltage of 60 V, providing an input voltage margin, and I had previous experience using it in other projects.

Input Protection

• Reverse Voltage Protection: An FET is used on the 54 V input.
• Transient Voltage Suppression: A TVS diode is employed to maintain circuit stability against voltage transients.

PSE Implementation

IP804AR - PSE IC

I used the IP804AR from ICplus as the PSE IC.

Features:

• Supports 4 ports, each capable of supplying up to 30 W.
• Uses internal FETs for switching PoE power, eliminating the need for additional external FETs.
• Can directly use the 54 VDC from the PoE adapter as the IC supply voltage.

Limitation: The IP804AR only supports PoE-related operations and does not handle Ethernet data communication.

IP175G - Ethernet Switch IC

To enable Ethernet data communication, I also used the IP175G, a 5-port Ethernet switch IC from ICplus.

PoE Configuration

• Mode B Operation: Since I'm using PoE in Mode B, I used PoE-specific transformers and RJ45 connectors.
• PoE+ Support: Aimed to support up to PoE+, so I selected components with higher specifications.
• Cost Consideration: Cost was not a major concern as there are no plans for mass production.

Integration with W55RP20-EVB-PICO

The key feature of the W55RP20-EVB-PICO PSE_KIT is that it can be used by connecting the W55RP20-EVB-PICO, as suggested by its name.

• Port Allocation:
  • Out of the 5 ports on the IP175G, 4 ports are connected via RJ45 connectors for UTP cable connections.
  • The remaining 1 port is connected to the Ethernet interface of the W55RP20-EVB-PICO.

Connection Method

Initially, to connect the Ethernet port of the W55RP20-EVB-PICO to the IP175G, I considered using the method from the impressive project "Wiznet Rudge PoE Pico PLC" by Manuel Alejandro Iglesias Abbatemarco.

• Issue: This method required removing the RJ45 connector from the W55RP20-EVB-PICO, and once manually soldered, replacing the board would be difficult.
• Solution: I opted to use pogo pins to connect the IP175G to the W55RP20-EVB-PICO.

Pogo Pin Details

• Type Used: Cupped Head pogo pins from Adafruit.

• Pin Arrangement: Positioned to contact pins 1, 2, 3, and 6 of the RJ45 connector on the W55RP20-EVB-PICO.

• Outcome: When mounting the W55RP20-EVB-PICO, the pogo pins accurately made contact without needing precise alignment.

PHY Connection

By connecting...