1

dc2583af

DEMO MANUAL DC2583A

Description

LT4294, LT4321

IEEE 802.3bt Powered Device

Demonstration circuit 2583 is an IEEE 802.3bt (Draft 2.3)

compliant Power over Ethernet (PoE) powered device

(PD). It features the LT®4294 PD interface controller and

the LT4321 PoE ideal diode bridge controller.

The LT4294 provides IEEE 802.3af (PoE, Type 1),

IEEE 802.3at (PoE+, Type 2) and IEEE 802.3bt (PoE++,

Type 3 and 4) compliant interfacing. It utilizes an external,

swap function to improve efficiency. Additional features

include power good (PWRGD) and T2P output indica-

tors for interfacing with downstream electronics. The

PWRGD output indicates the PD controller is ready to

provide power to the downstream load. This signal can be

used to enable an isolated power supply. The T2P output

indicates the available power from the power sourcing

L

, LT, LTC, LTM, Linear Technology, LTPoE++ and the Linear logo are registered trademarks of

Analog Devices, Inc. All other trademarks are the property of their respective owners.

BoarD photo

equipment (PSE) to the downstream load. This signal can

be used to limit the load and prevent overloading the PSE.

N-channel FETs to further improve end-to-end power

delivery efficiency and ease thermal design. This solu-

tion replaces the eight diodes typically found in a passive

PoE rectifier bridge.

The DC2583A accepts up to 71W of delivered power from

a 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.

Design files for this circuit board are available at

http://www.linear.com/demo/DC2583A

Top Side

Bottom Side