Silabs 公司的Si3452是四路高壓PoE和PoE+PSE端口控制器，每個器件支持四路PSE接口，PoE的可編電流限制為15.4W（350mA），PoE+的可編電流限制為30W(600mA)，專有系統可高達40W(850mA)，I2C接口不需要MCU，非常適合主系統的4-48端口低成本管理，支持IEEE 802.3af (PoE)和IEEE 802.3at (PoE+) PSE，主要用在以太網供電IEEE Std 802.3af 和802.3at端點的交換和中跨，支持大功率PD設備如Pan/Tilt/Zoom安全攝像設備，802.11n WAP，多頻帶多無線電WAP，安全和RFID系統，工業自動化系統，IP電話系統和iPBX, WiMAX ASN/BTS和CPE/ODU系統。本文介紹了Si3452主要特性，功能方框圖，應用框圖以及Si3452MS8 8端口評估板電路圖，RJ45連接器板電路圖和相應的材料清單。
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應用：
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
圖1。Si3452功能方框圖
圖2。Si3452四端口知接和主控制器連接框圖
圖3。Si3452 PSE應用框圖
Si3452MS8 8端口評估板
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.
圖4。Si3452評估板外形圖
圖5。Si3452評估板電路圖
圖6。Si3452評估板電路圖：DC/DC轉換器
圖7。Si3452評估板電路圖：Si3452連接器
圖8。RJ45連接器板電路圖
圖9。RJ45連接器板電路圖：LED驅動器
圖9。RJ45連接器板電路圖：連接器和耦合電路
Si3452 材料清單（BOM）：
RJ45連接器板材料清單：
詳情請見：
http://www.silabs.com/SupportDocuments/TechnicalDocs/Si3452.pdf
和
https://www.silabs.com/Support%20Documents/TechnicalDocs/Si3452MS8-KIT.pdf
