Features

• Compliant with IEEE 802.3at Type 1 and 2
• Low Power Dissipation
• 0.25Ω Sense Resistance Per Channel
• Very High Reliability 4-Point PD Detection
• 2-Point Forced Voltage
• 2-Point Forced Current
• High Capacitance Legacy Device Detection
• 1MHz I²C Compatible Serial Control Interface
• Midspan Backoff Timer
• Supports 2-Pair and 4-Pair Output Power
• Available in Multiple Power Grades
• LTC4274A-1: LTPoE++™ 38.7W
• LTC4274A-2: LTPoE++ 52.7W
• LTC4274A-3: LTPoE++ 70W
• LTC4274A-4: LTPoE++ 90W
• LTC4274C: PoE 13W
• Available in 38-Lead 5mm × 7mm QFN Package

Typical Application

Description

The LTC®4274A is a single Power Sourcing Equipment (PSE) controller capable of delivering up to 90W of LTPoE++ power to a compatible LTPoE++ Powered Device (PD). A proprietary detection/classification scheme allows mutual identification between a LTPoE++ PSE and LTPoE++ PD while remaining compatible and interoperable with existing Type 1 (13W) and Type 2 (25.5W) PDs. The LTC4274A feature set is a superset of the popular LTC4274. These PSE controllers feature low-RON external MOSFETs and 0.25Ω sense resistors which are especially important at the LTPoE++ current levels to maintain the lowest possible heat dissipation.

The LTC4274C targets fully automatic PSE systems powering Type 1 (up to 13W) PDs.

Advanced power management features include: a 14-bit current monitoring ADC, DAC-programmable current limit, and versatile quick port shutdown. PD Discovery uses a proprietary dual-mode 4-point detection mechanism ensuring excellent immunity from false PD detection. The LTC4274A/LTC4274C includes an I²C serial interface operable up to 1MHz.

The LTC4274A/LTC4274C is available in multiple power grades, allowing delivered PD power of 13W, 25.5W, 38.7W, 52.7W, 70W and 90W. These controllers are available in a 38-lead 5mm × 7mm QFN package.