Features

• Robust 35W PD Front End
• IEEE 802.3af Compliant
• Rugged 750mA Power MOSFET with Precision Dual Level Current Limit
• High Performance Synchronous Flyback Controller
• IEEE Isolation Obtained Without an Optoisolator
• Adjustable Frequency from 50kHz to 250kHz
• Tight Multi-Output Regulation with Load Compensation
• Onboard 25k Signature Resistor
• Programmable Classification Current to 75mA
• Complete Thermal and Over-Current Protection
• Available in Compact 32-Pin 7mm x 4mm DFN Package

Typical Application

Description

The LTC4268-1 is an integrated Powered Device (PD) controller and switching regulator intended for IEEE 802.3af and high power PoE applications up to 35W. By including a precision dual current limit, the LTC4268-1 keeps inrush below IEEE 802.3af current limit levels to ensure interoperability success while enabling high power applications with a 750mA operational current limit.

The LTC4268-1 synchronous, current-mode, flyback controller generates multiple supply rails in a single conversion providing for the highest system efficiency while maintaining tight regulation across all outputs. The LTC4268-1 includes Linear Technology’s patented NoOpto feedback topology to provide full IEEE 802.3af isolation without the need of optoisolator circuitry.

The oversized power path and high performance flyback controller of the LTC4268-1 combine to make the ultimate solution for power hungry PoE applications such as WAPs, PTZ security cameras, RFID readers and ultra-efficient 802.3af applications running near the 12.95W limit.

The LTC4268-1 is available in a space saving 32-pin DFN package.