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dc1814afe
DEMO MANUAL
DC1814A
Description
LTC4274A
Single LTPoE++ PSE Controller
Demonstration circuit 1814A features the
LTC
®
4274A
,
single port power sourcing equipment (PSE) controller,
capable of delivering up to 90W of LTPoE++
®
power to a
compatible LTPoE++ powered device (PD). A proprietary
detection/classification scheme allows mutual identifica-
tion between an LTPoE++ PSE and LTPoE++ PD while
remaining compatible and interoperable with existing
Type 1 (13W) and Type 2 (25.5W) PDs. The LTC4274A
feature set is a superset of the popular LTC4274. These
PSE controllers utilize low R
ON
external MOSFETs and
0.25Ω sense resistors which are especially important at
the LTPoE++ current levels to maintain the lowest possible
heat dissipation.
The LTC4274A is available in multiple power grades,
allowing delivered PD power of 13W, 25.5W, 38.7W,
52.7W, 70W and 90W. The DC1814A has four variations
DC1814A-A, DC1814A-B, DC1814A-C, and DC1814A-D
which accommodate the LTPoE++ power levels (Table 1).
L
, LT, LTC, LTM, LTPoE++, Linear Technology and the Linear logo are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
The LTC4274A is configured in the DC1814A as an AUTO
pin high, MID pin high, autonomous midspan power injec-
tor; input data from an existing network system is sent out,
along with power, to a PD. The LTC4274A autonomously
detects a PD, turns power on to the port, and disconnects
port power without the need for a microcontroller. A single
55V supply is required to power the DC1814A. A simple
LDO regulator circuit on the board powers the digital sup-
ply of the LTC4274A. A
SHDN
pushbutton shuts down the
port and disables detection. A
RESET
pushbutton resets
the LTC4274A to the AUTO pin high state.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1814A
Table 1. DC1814A Power Levels
DEMO BOARD
PSE CONTROLLER
MAXIMUM DELIVERED PD POWER
POWER SUPPLY*
DC1814A-A
LTC4274A-1
38.7W
72W
DC1814A-B
LTC4274A-2
52.7W
72W
DC1814A-C
LTC4274A-3
70W
120W
DC1814A-D
LTC4274A-4
90W
140W
*Recommended DC1814A power supply minimum to avoid drooping in a worst-case scenario with I
LIM
current at the port. Set the voltage between
54.75V to 57V for LTPoE++ compliance.
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