Linear公司的LTCR4270/LTC4271芯片組是12端口PSE控制器,專為IEEE 802.3at Type 1 and Type 2大功率兼容的PoE系統而設計,采用變壓器隔離通信協議來替代昂貴的光耦合器,可提供PD的最大功率為90W,支持兩對和4對輸出功率,1MHz I2C兼容的串行控制接口,主要用在PoE PSE交換/路由器和PoE PSE中跨.本文介紹了LTCR4270/LTC4271主要特性,典型應用電路和PoE系統框圖.
The LTCR4270/LTC4271 chipset is a 12-Port Power Sourcing Equipment (PSE) controller designed for use in IEEE 802.3at Type 1 and Type 2 (high power) compliant Power over Ethernet (PoE) systems. Transformer-isolated communication protocol replaces expensive opto-couplers and complex isolated 3.3V supply resulting in significant BOM cost savings. The LTC4270/LTC4271 chipset delivers lowest-in-industry heat dissipation by utilizing low-RDS(ON) external MOSFETs and 0.25Ω sense resistors.
Advanced power management features include per-port 12- bit current monitoring ADCs, DAC-programmable current limit, and versatile fast shut-down of preselected ports.
Advanced power management host software is available under a no-cost license. PD Discovery uses a proprietary dual-mode 4-point detection mechanism ensuring excellent immunity from false PD detection. Midspan PSEs are supported with 2-event classification and a 2 second backoff timer. The LTC4270/LTC4271 includes an I2C serial interface operable up to 1MHz.
The LTC4270/LTC4271 is available in multiple power grades allowing delivered PD power up to 90W.
LTCR4270/LTC4271主要特性:
12 Independent PSE Channels
Compliant with IEEE 802.3at Type 1 and 2
Chipset Provides Electrical Isolation
Reduced BOM Cost
Eliminates up to 6 High Speed Opto-Couplers
Eliminates Isolated 3.3V Power Supply
Low Power Dissipation
0.25Ω Sense Resistance Per Channel
Very High Reliability 4-Point PD Detection
2-Point Forced Voltage
2-Point Forced Current
Temperature Monitoring
VEE and VPORT Monitoring
1 Second Rolling IPORT Averaging
Supports 2-Pair and 4-Pair Output Power
1MHz I2C Compatible Serial Control Interface
Available In Three Power Grades
A-Grade – LTPoE++™ 35W to 90W
B-Grade – PoE+ 25.5W
C-Grade – PoE 13W
Available In 52-Lead 7mmx?8mm (LTC4270) and 24-Lead 4mm x?4mm (LTC4271) QFN Packages
LTCR4270/LTC4271應用:
PoE PSE Switches/Routers
PoE PSE Midspans
圖1.LTCR4270/LTC4271典型應用電路(1)
圖2.LTCR4270/LTC4271 PoE系統框圖
圖3.LTCR4270/LTC4271專用解決方案電路
圖4.LTCR4270/LTC4271典型應用電路(2)
詳情請見:
http://cds.linear.com/docs/Datasheet/42701f.pdf
