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LTC4270/LTC4271 - 12-Port PoE/PoE+/LTPoE++ PSE Controller

The LTC®4270/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.

Features 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 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++™ 38.7W to 90W B-Grade – PoE+ 25.5W C-Grade – PoE 13W Available In 52-Lead 7mm × 8mm (LTC4270) and 24‑Lead 4mm × 4mm (LTC4271) QFN Packages Typical Application

Applications PoE PSE Switches/Routers PoE PSE Midspans Packaging

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