LTC4269 IEEE 802.3at PoE+ Controller with Aux Supp

By Linear Technology 53

LTC4269 IEEE 802.3at PoE+ Controller with Aux Supp

Power by Linear™/Analog Devices LTC4269 is an integrated powered device (PD) controller and switching regulator intended for high power IEEE 802.3at and 802.3af applications. The controller is targeted for high efficiency, single and multi-output applications from 10 W to 25 W. By supporting both 1-event and 2-event classifications, as defined by the IEEE, the LTC42691 can be used in a wide range of product configurations.

The LTC4269 synchronous, current mode, flyback controller generates multiple supply rails in a single conversion step providing for the highest system efficiency while maintaining tight regulation across all outputs. The controller includes patented no-opto feedback topology to provide full IEEE 802.3 isolation without the need of an optoisolator circuit. A true soft-start function allows graceful ramp-up of all output voltages.

All PD solutions from ADI include a shutdown pin to provide flexible auxiliary power options. The LTC4269 can accommodate adapter voltages from 18 V to 60 V and supports both PoE or aux dominance options. The LTC4269 is available in a 32-pin DFN package and is ideal for 802.11n, IP phones, and PTZ security cameras.

Features
  • •PoE+ 2-event classification
  • •25.5 W IEEE 802.3at compliant (Type 2) PD
  • •Integrated state-of-the-art synchronous flyback controller
    • •Isolated power supply efficiency >92%
    • •88% efficiency including diode bridge and hot swap™ FET
  • •Flexible auxiliary power interface
  • •Superior EMI performance
  • •Robust 100 V 0.7 Ω (typ) integrated hot swap MOSFET
  • •IEEE 802.3at high power available indicator
  • •Integrated signature resistor and programmable class current
  • •Undervoltage, overvoltage, and thermal protection
  • •Short-circuit protection with auto-restart
  • •Programmable switching frequency from 100 kHz to 500 kHz
  • •Complementary power good indicators
  • Robust 100 V 0.7 Ω (typ) integrated Hot Swap MOSFET
  • •Integrated signature resistor, programmable class current, UVLO, OVLO, and thermal protection
Applications
  • Dual radio 802.11n access points
  • IP phones with large color screens
  • PTZ security cameras

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