Demonstration Circuit 2476A is an Ethernet Alliance™ Gen 2 PoE certified IEEE 802.3bt compliant power over ethernet (PoE) powered device (PD). It features the LT4295 PD interface and switching regulator controller and the LT4321 PoE ideal diode bridge controller. It features the LT4295 PD interface and switching regulator controller and the LT4321 PoE ideal diode bridge controller.
The LT4295 provides IEEE 802.3af (PoE, Type 1), IEEE 802.3at (PoE+, Type 2), and IEEE 802.3bt (PoE++, Type 3 and 4) compliant interfacing and power supply control. It utilizes an external, low RDS(on) (30mΩ typical) N-channel FET for the hot swap function to improve efficiency. The LT4295 controls a DC/DC converter that utilizes a highly efficient 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 solution replaces the eight diodes typically found in a passive PoE rectifier bridge.
The DC2476A-A accepts up to 71.3W of delivered power from a power sourcing equipment (PSE) via the RJ45 connector (J1) or a local 48V DC power supply using the auxiliary supply input. When both supplies are connected, the auxiliary supply input has priority over the PoE input. The DC2476A-A supplies a 24V output at up to 2.7A as a Class 8 (71.3W) PD and up to 2.4A as a Class 7 (62W) PD application.