Linear Technology Corp. has introduced the LTC4270/LTC4271 isolated 12-port Power Source Equipment (PSE) controller chipset designed for use in IEEE 802.3at (PoE+) Type 1 and Type 2 compliant Power over Ethernet (PoE) systems. 

The LTC4270/71 provides 12 independent PSE channels for simpler, lower component count designs, reduced board space and lower costs.  The LTC4271 provides a digital interface to the PSE host, while the LTC4270 provides the high voltage Ethernet interface; the two ICs are then bridged by inexpensive Ethernet transformers.  The transformer-isolated communication protocol replaces up to six expensive opto-couplers and a complex isolated 3.3V supply used in traditional designs, resulting in significant cost savings. 

PSE applications include next generation switches, routers, hubs and midspans.  The devices feature 80V port pins and very low power dissipation, making thermal design significantly easier than designing with PSEs that integrate more fragile normally higher RDS(ON) MOSFETs. 

Key highlights:

•12 Independent PSE Channels
•Compliant with IEEE 802.3at Type 1 and 2
•Chipset Provides Electrical Isolation
  Reduce BOM Cost
  Eliminates up to 6 High Speed Opto-Couplers
  Eliminates Isolated 3.3V Power Supply

•Low Power Dissipation
  0.25Ohm Sense Resistance per Channel

•Very High Reliability 4-Point PD Detection
  2-Point Forced Voltage
  2-Point Forced Current

•Temperature Monitoring
•VEE & VPORT Monitoring
•1 Second Rolling IPORT Averaging
•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 7mm x 8mm (LTC4270) & 24-Lead 4mm x 4mm (LTC4271)QFN Packages