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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 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,
low R
DS(ON)
(57mΩ typical) N-channel FET for the hot
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.
The LT4321 controls eight low R
DS(ON)
(57mΩ typical)
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
