Analog Devices LT4295 | Demoboard DC2539A-A

Description

Demonstration circuit 2539A is an IEEE802.3bt (Draft 2.1)compliant Power over Ethernet (PoE) Powered Device(PD). It features the LT®4295 PD interface and switchingregulator controller and the LT4321 PoE ideal diodebridge controller.The LT4295 provides IEEE802.3af (PoE, Type 1),IEEE802.3at (PoE+, Type 2), and IEEE802.3bt (PoE++,Type 3) compliant interfacing and power supply control. Itutilizes an external, low RDS(ON) (57mΩ typical) N-channelFET for the hot swap function to improve efficiency. TheLT4295 controls a DC/DC converter that utilizes a highlyefficient Flyback topology with synchronous rectification.The LT4321 controls eight low RDS(ON) (30mΩ 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 DC2539A-A accepts up to 51W 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 DC2539A-A supplies a 12V output at up to 3.9A.

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