Power over Ethernet - How it Works
- Power Sourcing Equipment (PSE) transmitted a maximum of 15.4W which assured delivery of 12.95W (350mA) to the Powered Device (PD)
- Total throughput was limited to 100Mbps and allowed power to be distributed over only two pairs, and in two different modes (Mode A and Mode B) as seen in Figure 1 below.
IEEE 802.3at (2009)
- Power Sourcing Equipment (PSE) transmitted a maximum of 30W which assured delivery of 25.5W (600mA) to the Powered Device (PD)
- Total throughput was limited to 1000 Mpbs or 1Gbps
- The same Mode A and Mode B were used again, and the same pairs are used to transmit power. The difference with 802.3at is that all four pairs are used to transmit data packets to achieve 1Gbps throughput (Figure 2).
IEEE 802.3bt (20198)
- Two power levels: Type 3 - 60W from Power Sourcing Equipment (PSE) and 50W assured at Powered Device (PD) side. Type 4 - about 90W from PSE and about 80W assured at PD side.
- All four pairs transmit data packets and power
- Total throughput is10Gbps, a 10x increase over previous generations
- Backwards compatible with previous generations of PoE; 802.3af and 802.3at
- Figure 3 illustrates a proposed 4-pair power delivery solution