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Zip: 518108

Phone: +86-755-26511956

Fax: +86-755-26511956-801

Cell: +86-17603067633

Web: www.optic-solutions.com

Email: optfocus005@optfocus.com

POE power supply principle and power supply process
Aug 15, 2017

1. Initially, the PSE device outputs a very small voltage at the port until it detects that the cable terminal is connected to a receiving terminal that supports the IEEE 802.3af standard.

2. PD device classification

When the receiving device PD is detected, the PSE device may classify the PD device and evaluate the power loss required by the PD device.

3. Start power supply

During a configurable time (typically less than 15μs), the PSE device begins to supply power from the low voltage to the PD device until a 48V DC power supply is provided.

4. Power supply

For the PD device to provide a stable and reliable 48V DC power to meet the PD device does not exceed 15.4W power consumption.

5. Power off

If the PD is disconnected from the network, the PSE will quickly power the PD device (typically within 300 to 400 ms) and repeat the detection process to detect if the terminal of the cable is connected to the PD.


Power supply method

The PoE standard defines two methods for transporting DC to POE-compliant devices using Ethernet transmission cables:

Mid-Span (Mid-Span)

The use of idle cable pairs that are not used in Ethernet cables to transmit DC power between the switch and the network terminal equipment can be used to power the network terminal equipment through the network cable. The Midspan PSE is a dedicated power management Equipment, usually put together with the switch. It corresponds to each port has two RJ45 jacks, one with a short-term connection to the switch, the other connected to the remote device.

poe switch.4.png

Mid-Span

The use of idle cable pairs that are not used in Ethernet cables to transmit DC power between the switch and the network terminal equipment can be used to power the network terminal equipment through the network cable. The Midspan PSE is a dedicated power management Equipment, usually put together with the switch. It corresponds to each port has two RJ45 jacks, one with a short-term connection to the switch, the other connected to the remote device.


End-Span

End-Span is the transmission of data used in the core line at the same time transmission of direct current, the transmission and Ethernet data using a different frequency. The corresponding Endpoint PSE (Terminal Power Supply) has POE-enabled Ethernet switches, routers, hubs, or other network switching devices. It is envisioned that End-Span will be promoted quickly because Ethernet data and transmission uses a common line pair, eliminating the need for a dedicated line for independent transmission, which is for only 8-core cables and matching standard RJ- 45 socket significance is particularly important.