When installing wireless transmission equipment, POE is a device that is often encountered. Most ordinary POE interfaces are of the 100 Mbps type. However, with the advancement of wireless transmission technology, many 802.11AC type devices nowadays have 1000 Mbps interfaces. This means that the POE required for powering them also needs to use 1000 Mbps POE. So, what are the differences in power supply between 100 Mbps POE and 1000 Mbps POE? Today, we will explain this to you.

Standard Category 5 network cables have four pairs of twisted wires, but in 10MBASE-T and 100M BASE-T standards, only two of these pairs are used.

‌I. In the IEEE 802.3af standard, 100 Mbps can be achieved using two connection methods:

1.Use the idle power supply. Connect the positive terminals of 4 and 5, and the negative terminals of 7 and 8.

If the 48V power supply is transmitted through the idle lines (4, 5, 7, 8)

The 100-megabit PoE transmits data using the 1, 2, 3, and 6 wire sequences, while providing power through the 4, 5, 7, and 8 wire sequences.

2. Use the signal lines (1, 2, 3, 6) to simultaneously transmit signals and 48V power supply.

When applying data power supply, connect the DC power to the key points of the transmission transformer. In this way, the pairs 1, 2 and 3, 6 of the lines can have any polarity. The core line used for transmitting data can simultaneously transmit direct current, and the transmission adopts a different frequency from the Ethernet data signal, which does not affect the data transmission.

II. Gigabit BASE-T PoE Power Supply System

The 4 wire pairs of the PoE power supply system all transmit data, so there are no idle pairs. They all use the data pairs for power supply. In Figure 6, the 1st, 2nd, 3rd, and 6th pins are connected through the network transformer for frequency division and separation of voltage and signal. The separated voltage is then linked to the bridge rectifier for rectification and power supply, as shown in the following figure:

III. PoE Working Process

In words, when deploying PSE devices in a network, the PoE power supply process is as follows:

Test: Initially, PSE will output a very small voltage until it detects that the cable terminal is connected to a standard power receiving device.

PD-end equipment: Once the receiving-end equipment PD is detected, the PSE can classify the PD equipment and assess the power consumption required by this PD device.

Power supply starts: Within a configurable period of time, the PSE device begins to supply power from a low voltage to the PD device, until reaching a 48V DC power supply.

Power Supply: Provide stable and reliable 48v DC power to the PD equipment. The total power consumption of the equipment should not exceed 15.4w.

Power outage: If the PD device disconnects from the network, the PSE will immediately stop supplying power to the device and repeatedly check whether the terminal is still connected to the PD device.