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[原创] Linear LTC4279单端口以太网(PoE)供电设备控制方案

关键词:电源管理 以太网(PoE)供电 PoE PoE+ LTPoE++ PSE

时间:2017-02-22 10:33:52       作者:Linear       来源:中电网

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IEEE 802.3at 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 sourcing equipment (PSE) controller designed for use in IEEE 802.3at Type 1, Type 2 and LTPoE++ compliant Power over Ethernet (PoE) systems. The LTC4279 provides fully autonomous IEEE 802.3 and LTPoE++ compliant operation without a microcontroller. The LTC4279 simplifies PSE implementation, requiring only a single supply and a small number of passive support components.

The LTC4279 delivers lowest-in-industry heat dissipation by utilizing a low-RDS(ON) external MOSFET and a 0.1Ω sense resistor, eliminating the need for expensive heat sinks and increasing efficiency.

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

Legacy and custom PDs are supported with pin-selectable LEGACY and UltraPWR modes. LEGACY mode detects and powers pre-IEEE specification PDs. UltraPWR mode
aggressively turns on and powers custom PDs requiring high 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 Current Thresholds
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)
PoE Midspan Power Injectors
Power Forwarders
Femto Cells
Security Systems

图1.以太网供电(PoE)系统框图

图2.双认证PD以太网供电(PoE)系统框图

图3. LTC4279应用电路(1)

图4. LTC4279应用电路(2)

图5. LTC4279应用电路(3)

图6. LTC4279应用电路(4)

演示板DC2541A

Demonstration circuit 2541A features the LTC®4279, an autonomous single port Power Sourcing Equipment (PSE) controller for use in IEEE 802.3at Type 1, Type 2 and LTPoE++® compliant Power over Ethernet (PoE) systems. The LTC4279 simplifies IEEE and LTPoE++ PSE implementation, requiring only a 45-57V supply and a small number of passive support components.

The DC2541A provides jumper selections for setting the LTC4279 power mode, LEGACY pin, DUALPD pin, and MID pin, as well as the PSE output 2-pair or 4-pair mode.

A pushbutton switch resets the LTC4279. LEDs indicate main supply power and output power are up. The Data-In RJ45 connects to a PHY data source and the Data-and- Power-Out RJ45 connects to a PD.

图7. 演示板DC2541A连接图

图8. 演示板DC2541A电路图

演示板DC2541A材料清单:




图9. 演示板DC2541A PCB顶层装配图

图10. 演示板DC2541A PCB顶层设计图

图11. 演示板DC2541A PCB层2设计图

图12. 演示板DC2541A PCB层3设计图

图13. 演示板DC2541A PCB底层设计图

图14. 演示板DC2541A PCB底层装配图
详情请见:
http://cds.linear.com/docs/en/datasheet/4279f.pdf

http://cds.linear.com/docs/en/demo-board-manual/DC2541AF.PDF
以及http://cds.linear.com/docs/en/demo-board-schematic/DC2541A2-SCH.PDF

4279f.pdf

DC2541A2-SCH.PDF

DC2541AF.PDF

 

 

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