Analog Devices INEAR TECHNOLOGY DC2583A Demo Manual

Description
Demonstration circuit 2583 is an IEEE 802.3bt (Draft 2.3)
compliant Power over Ethernet (PoE) powered device
(PD). It features the LT 4294
®
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,
low R (57mΩ typical) N-channel FET for the hot
DS(ON)
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
BoarD photo
PD interface controller and
Top Side
DEMO MANUAL DC2583A
IEEE 802.3bt Powered Device
equipment (PSE) to the downstream load. This signal can
be used to limit the load and prevent overloading the PSE.
The LT4321 controls eight low R
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
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.
LT4294, LT4321
(57mΩ typical)
DS(ON)
Bottom Side
dc2583af
1