Analog Devices LT4295 | Demoboard DC2475A-A

Description

Demonstration circuit 2475A-A is an IEEE802.3bt (Draft 2.0)compliant Power over Ethernet (PoE) powered device (PD).It features the LT®4295 PD interface and switching regulatorcontroller with the LT4321 PoE ideal diode bridge controller.The LT4295 provides IEEE802.3af (PoE, Type 1),IEEE802.3at (PoE+, Type 2), and IEEE802.3bt (PoE++,Type 3 and 4) compliant interfacing and power supplycontrol. It utilizes an external, low RDS(ON) (57mΩ typical)N-channel FET for the Hot Swap function to improveefficiency. The LT4295 controls a DC/DC converter thatutilizes a highly efficient flyback topology with synchronousrectification.The LT4321 controls eight low RDS(ON) (57mΩ typical)N-channel FETs to further improve end-to-end power delivery efficiency and ease thermal design. This solutionreplaces the eight diodes typically found in a passive PoErectifier bridge.The DC2475A-A accepts up to 40W of delivered powerfrom a power sourcing equipment (PSE) via the RJ45connector (J1) or a local 48VDC power supply using theauxiliary supply input. When both supplies are connected,the auxiliary supply input has priority over the PoE input.The DC2475A-A supplies a 12V output at up to 3A.

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