原标题：Silabs Si3452四路高压PoE+PSE端口控制方案

　　Silabs 公司的Si3452是四路高压PoE和PoE+PSE端口控制器，每个器件支持四路PSE接口，PoE的可编电流限制为15.4W(350mA)，PoE+的可编电流限制为30W(600mA)，专有系统可高达 40W(850mA)，I2C接口不需要MCU，非常适合主系统的4-48端口低成本管理，支持IEEE 802.3af (PoE)和IEEE 802.3at (PoE+) PSE，主要用在以太网供电IEEE Std 802.3af 和802.3at端点的交换和中跨，支持大功率PD设备如Pan/Tilt/Zoom安全摄像设备，802.11n WAP，多频带多无线电WAP，安全和RFID系统，工业自动化系统，IP电话系统和iPBX, WiMAX ASN/BTS和CPE/ODU系统。本文介绍了Si3452主要特性，功能方框图，应用框图以及Si3452MS8 8端口评估板电路图，RJ45连接器板电路图和相应的材料清单。

　　QUAD HIGH-VOLTAGE PORT CONTROLLER FOR POE AND POE+ PSES

　　When connected directly to the host system or configured in Auto mode, each Si3452 high-voltage port controller provides all of the critical circuitry and sophisticated power measurement functionality for the high-voltage interfaces of four complete PSE ports. The Si3452 fully integrates robust, low-RON (0.3 ohm typical) power MOSFET switches, low-power dissipation current sensing circuitry, and transient voltage surge suppression devices.

　　The on-chip current sense circuitry and power MOSFETs provide programmable scaling of current limits to match either PoE (350 mA, 15.4 W), PoE+ (600 mA, 30 W), and extended (800 mA, 40 W) power requirements on a perport basis. Designed for use in Endpoint PSE (e.g., Ethernet switches) or Midspan PSE (e.g., inline power injectors) applications, each Si3452 also performs the IEEE-required powered device (PD) detection, classification, and disconnect functionality.

　　The flexible architecture enables powered device disconnect detection using Silicon Laboratories’ proprietary dV/dt disconnect sensing algorithm. dV/dt disconnect is an alternative to dc disconnect that requires no additional BOM components, does not dissipate extra device power, and fully interoperates with all powered devices. Also provided are multi-point detection algorithms and per-port current and voltage monitoring.Intelligent protection circuitry includes power supply undervoltage lockout (UVLO), port output current limiting and short-circuit protection, thermal overload sensing and port shutdown, and transient voltage surge suppressors capable of protecting the Si3452 from a variety of harsh surge events seen on the RJ-45 interface.

　　To maximize system design flexibility and minimize cost, each Si3452 connects directly to a system host controller through an I2C serial interface, eliminating the need for an external MCU. The Si3452 can be set to one of 12 unique addresses, allowing control of up to 48 ports on a single I2C bus.

　　Si3452主要特性：

　　Each Si3452 high-voltage port controller supports four PSE power interfaces

　　Programmable current limits for PoE (15.4 W), PoE+ (30 W), and proprietary systems (up to 40 W) per port

　　I2C interface requires no external MCU for easy, low-cost management of 4 to 48 ports by the host system

　　Unique mixed-signal IC high-voltage component integration simplifies design, lowers power dissipation, minimizes external BOM, and reduces PCB footprint

　　Internal low-RON power FETs with current-sense circuitry

　　Integrated transient voltage surge suppressors

　　Proprietary dV/dt disconnect sensing methods

　　Industrial (–40 to 85 ℃) operating temperature

　　Compact, 6×6 mm2, 40-pin QFN RoHS-compliant package

　　Programmable architecture supports IEEE 802.3af (PoE) and IEEE 802.3at (PoE+) PSEs

　　Programmable current limits for PoE (350 mA) and PoE+ (600 mA), and custom limits to 850 mA

　　Per-port current and voltage monitoring for sophisticated power management and control

　　Power policing mode

　　Robust multi-point detection

　　Supports 1-Event and 2-Event classification algorithms Comprehensive, robust, faultprotection circuitry

　　Supply undervoltage lockout (UVLO)

　　Output current limit and shortcircuit protection

　　Foldback current limiting

　　Dual-threshold thermal overload protection

　　Fault source reporting for intelligent port management

　　Si3452应用：

　　Power over Ethernet Endpoint switches and Midspans for IEEE Std 802.3af and 802.3at Supports high-power PDs, such as:

　　Pan/Tilt/Zoom security cameras

　　802.11n WAPs

　　Multi-band, multi-radio WAPs

　　Security and RFID systems

　　Industrial automation systems

　　Networked audio

　　IP Phone Systems and iPBXs

　　Metropolitan area networked WAPs, cameras, and sensors

　　WiMAX ASN/BTS and CPE/ODU Systems

　　图1。Si3452功能方框图

　　图2。Si3452四端口知接和主控制器连接框图

　　图3。Si3452 PSE应用框图

　　Si3452MS8 8端口评估板

　　The Si3452MS8 8-port evaluation kit (Si3452MS8-KIT) is intended for Power over Ethernet (PoE) Power Sourcing Equipment (PSE) system designers interested in evaluating the Quad-port Si3452 PSE controller. While evaluation kits are normally shipped with Si3452 devices that use Silicon Laboratories’ proprietary dV/dt™ disconnect, they can also be used for evaluation of the pin-compatible Si3453, which uses dc disconnect. In this case, the Si3452 devices must be replaced with the appropriate Si3453 device. Please refer to “8. Ordering Guide” on page 38 for more information.

　　The Si3452 is controlled through an I2C (or SMBus) interface. For convenience in evaluation, a graphical user interface (GUI) is provided, giving an easy-to-use visual display and control of the Si3452 I2C registers. The evaluation kit assumes the user has access to a PC to control the evaluation board with the provided GUI.

　　The user is also responsible for providing an appropriate high-voltage power supply. The power supply should be 45 to 57 V for normal PoE or 51 to 57 V for PoE+. The Si3452 can supply over 30 W to each port. Thus, the two Si3452 controllers for the eight port demo system can provide over 240 W of total power. Normally, a 50 to 100 W power supply is used. While the classification and actual current consumption of each port is available, the demo GUI does not implement system-level power management. Contact Silicon Laboratories for more information about system-level power management options.

　　The Si3452MS8 kit has been thoroughly tested for standards compliance and interoperability. Contact Silicon Laboratories for test reports using Sifos PoE test equipment and University of New Hampshire PoE standards compliance and interoperability reports.

　　图4。Si3452评估板外形图

　　图5。Si3452评估板电路图

　　图6。Si3452评估板电路图：DC/DC转换器

　　图7。Si3452评估板电路图：Si3452连接器

　　图8。RJ45连接器板电路图

　　图9。RJ45连接器板电路图：LED驱动器

　　图9。RJ45连接器板电路图：连接器和耦合电路

　　Si3452 材料清单(BOM)：

　　RJ45连接器板材料清单：