Linear LTC4279单端口以太网(PoE)供电设备控制方案

Linear公司的LTC4279是自主单端口以太网(PoE)供电设备控制器,适用于IEEE802.3at Type 1, Type 2和LTPoE++兼容的以太网(PoE)供电系统.不需要MCU就能完全自主进行IEEE 802.3和LTPoE++兼容的操作.仅需要单元和一些无源元件就能实现供电设备(PSE),支持LTPoE++高达90W功率,支持2线和4线输出功率.主要用在PoE PSE端点(交换机/路由器),PoE中跨电源,电源转送,飞蜂窝(Femto Cell)以及安全系统.本文介绍了LTC4279主要特性,框图和以太网供电(PoE)系统框图,多种应用电路,以及演示板DC2541A主要特性,电路图和材料清单,PCB设计图.

The LTCR4279 is an autonomous single port power sourcingequipment (PSE) controller designed for use in IEEE802.3at Type 1, Type 2 and LTPoE++ compliant Powerover Ethernet (PoE) systems. The LTC4279 provides fullyautonomous IEEE 802.3 and LTPoE++ compliant operationwithout a microcontroller. The LTC4279 simplifies PSEimplementation, requiring only a single supply and a smallnumber of passive support components.

The LTC4279 delivers lowest-in-industry heat dissipationby utilizing a low-RDS(ON) external MOSFET and a 0.1Ωsense resistor, eliminating the need for expensive heatsinks and increasing efficiency.

PD discovery uses a proprietary dual-mode 4-point detectionmechanism ensuring excellent immunity from falsePD detection. Midspan PSEs are supported with physical　layer classification and a 2.5 second backoff timer.

Legacy and custom PDs are supported with pin-selectableLEGACY and UltraPWR modes. LEGACY mode detectsand powers pre-IEEE specification PDs. UltraPWR mode aggressively turns on and powers custom PDs requiringhigh inrush and/or operational currents.

LTC4279主要特性:

Compliant with IEEE 802.3at Type 1 and 2
Supports LTPoE++® Up to 90W
Supports Dual-Signature PDs
Fully Autonomous Operation without Microcontroller
Very Low Power Dissipation
–0.1Ω Sense Resistance
–Low RDS(ON) External MOSFET
Very High Reliability 4-Point PD Detection
–2-Point Forced Voltage and Forced Current
Robust Short-Circuit Protection
Cable Surge Protected ±80V OUT pin
Classification Dependent ICUT and ILIM CurrentThresholds
Supports 2-Pair and 4-Pair Output Power
UltraPWR Mode Supports Custom PDs up to 123W
Pin-Selectable Detection Backoff Timer for Midspans
Pin Programmable Legacy PD Detection
Pin Programmable Maximum Power Mode
Status LED Pin
Available in 20-Pin QFN and 16-Pin SO Packages

LTC4279应用:

PoE PSE Endpoints (Switch/Router)
PoEMidspan Power Injectors
Power Forwarders
Femto Cells
Security Systems

The DC2541A provides jumper selections for setting theLTC4279 power mode, LEGACY pin, DUALPD pin, andMID pin, as well as the PSE output 2-pair or 4-pair mode. A pushbutton switch resets the LTC4279. LEDs indicatemain supply power and output power are up. The Data-InRJ45 connects to a PHY data source and the Data-and-Power-Out RJ45 connects to a PD.

详情请见:

和
以及
4279f.pdf
DC2541A2-SCH.PDF

(编辑：mao35  来源：网络整理)