Analog Devices' Power by Linear: LT4276 - LTPoE++/PoE+/PoE PD Forward/Flyback Controller

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The LT®4276 is a pin-for-pin compatible family of IEEE 802.3 and LTPoE++ Powered Device (PD) controllers. It includes an isolated switching regulator controller capable of synchronous operation in both forward and flyback topologies with auxiliary power support.

The LT4276 LTPoE++, PoE+ and PoE compliant powered device (PD) interface controllers for applications requiring 2 to 90 W of delivered power. The LT4276 integrates a PD controller and an isolated switching regulator controller, capable of synchronous operation in both forward and flyback topologies with auxiliary power support. This integration simplifies front end PD designs by reducing component count and board space, allowing the LT4276A (LTPoE++), LT4276B (PoE+) and LT4276C (PoE) to efficiently deliver power to PD loads using just one IC.

Analog Devices' Power by Linear’s LTPoE++ standard extends support for today’s class of very high power applications, such as picocell base stations, signage and heated outdoor security cameras, by expanding the power budget to four new power levels (38.7 W, 52.7 W, 70 W and 90 W). Unlike traditional PD controllers that integrate the power MOSFET, the LT4276 controls an external MOSFET to drastically reduce overall PD heat dissipation and maximize power efficiency, especially important at higher power levels. This novel approach allows users to size the MOSFET to their application’s specific heating and efficiency requirements, enabling the use of MOSFETs with as low as 3.0 mΩ R where necessary. A 100 V rated input voltage means the LT4276 easily survives and protects PDs from the most common Ethernet line surges.


IEEE802.3af/at and LTPoE++™ 90W Powered Device (PD) with Forward/Flyback Controller

LT4276A Supports All of the Following Standards:

LTPoE++ 38.7 W, 52.7 W, 70 W and 90 W

- IEEE 802.3at 25.5 W Compliant

- IEEE 802.3af up to 13 W Compliant

- LT4276B is IEEE 802.3at/af Compliant

- LT4276C is IEEE 802.3af Compliant

- Superior Surge Protection (100 V Absolute Maximum)

- Wide Junction Temperature Range (-40 °C to 125 °C)

- Auxiliary Power Support as Low as 9 V

- No Opto-Isolator Required for Flyback Operation

- External Hot Swap™ N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency

- > 94 % End-to-End Efficiency with LT4321 Ideal Bridge

- Available in a 28-Lead 4 mm x 5 mm QFN Package


High Power Wireless Data Systems

- Outdoor Security Camera Equipment

- Commercial and Public Information Displays

- High Temperature Applications

Linear Technology LT4276 LTPoE PoE PoE PD Forward Flyback Controller secondary 1

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