【Introduction】With the rapid development of new services such as WLAN, VoIP, and network video surveillance, a large number of IP-based terminals such as Wireless LAN AP, IP Phone, and IP Camera appear around our lives. These devices are usually numerous in number, special in location, complicated in the wiring of data power cables, and difficult to obtain power for the devices. Therefore, the PoE (Power Over Ethernet) power supply technology emerges as the times require. Especially with the development of network video surveillance systems and the popularization of 5G small base stations and CPE equipment in the future, POE power supply will also usher in new development opportunities.
POE power supply system
A collection of advantages of POE power supply
POE power supply, in short, can transmit both data and power on the same network cable. The above picture shows the POE power supply system applied in the high-definition network digital monitoring platform. The POE system includes two parts, the power supply equipment (PSE) and the power receiving equipment (PD).
POE power supply mode
In order to standardize the PoE power supply equipment, the industry generally adopts IEEE802.3af/IEEE802.3at as the international standard of the Ethernet power supply system, and the protocol defines the power supply mode of the network port.
◾Alternative A: Use signal lines (1, 2, 3, 6) to transmit data signals and 48V power at the same time;
◾Alternative B: Use idle lines (4, 5, 7, 8) to transfer 48V power;
As a power supply chip and power supply solution provider, MPS has been deeply involved in the security and network communication industry for many years. After deeply understanding the actual needs and technical difficulties of engineers for POE power supply solutions, MPS has developed a complete set of POE solutions including PSE and PD.
Part 1 PSE Controller
MP3924 — PSE Controller/IEEE802.3af/at
MP3924 is a new digital PSE controller introduced by MPS, with flexible parameter configuration to facilitate customers to realize power distribution and over-power protection.
◾Support four ports, each port is equipped with a 0.25Ω current sensing resistor and the maximum output power of each port is up to 40W
◾ Four ports correspond to 4-bit programmable I2C address, which can accurately assign and monitor the current and voltage of each port through I2C
◾It comes with power classification for each port, and the over-power point of the total power can be set through the PMAX pin
◾With DC disconnection detection function, this function can be enabled or disabled through I2C or external AUTO pin
MP3924 – Operating Mode
Test conditions: Vin=48V, ports 1, 2, and 4 are connected to PD, and port 3 is floating.
◾Ports 1, 2, and 4 are connected to the PD, so the power-on is successful after the normal protocol handshake
◾Port 3 is not connected to PD, and it is always in the state of PD detection
Part 2 PD Controller
MP8009 — PD Controller/IEEE802.3af/at
12W MP8009 Active Clamp Primary-Side Feedback Flyback Scheme
Application Specifications: Vin=36V-57V, Vout=12V/1A
◾MP8009 load regulation rate <1% (50mA~1A), efficiency up to 91%
25W MP8009 Primary-Side Feedback Flyback Solution
Application Specifications: Vin=9V-57V, Vout=12V/2.1A
◾MP8009 supports primary side feedback and secondary side feedback, engineers can choose the feedback method according to product requirements
◾The minimum switching frequency is limited to more than 30KHz, which avoids the problem of light-load whistling of the transformer; the maximum frequency of MP8009H can reach 450KHz, which helps engineers optimize the volume of the transformer
◾At the same time, it supports the active clamp forward scheme, and the efficiency is as high as 92% under the condition of 5V/5A
◾Using frequency jittering technology to help engineers optimize EMI
POE technology has the advantages of easy installation, easy management, security and stability, and has huge application prospects. In terms of future development trends, the power supply will become larger and larger, and more and more terminal devices will be supported, so the efficiency requirements for POE equipment will become higher and higher.
With its own advantages and in-depth cooperation with the security and Netcom industries, MPS will become the leader of the POE power supply architecture.