1
dc1815afc
DEMO MANUAL DC1815A
Description
LTC4266A
Quad LTPoE++ PSE Controller
Demonstration circuit 1815A features the
quad
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 identification between
an LTPoE++ PSE and LTPoE++ PD while remaining com-
patible and interoperable with existing Type 1 (13W) and
Type 2 (25.5W) PDs. The LTC4266A feature set is a superset
of the popular LTC4266. 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 LTC4266A is available in multiple power grades, allow-
ing delivered PD power of 13W, 25.5W, 38.7W, 52.7W, 70W
and 90W. The DC1815A has four variations DC1815A-A,
DC1815A-B, DC1815A-C, and DC1815A-D which accom-
modate the four LTPoE++ power levels (Table 1).
Advanced power management features of the LTC4266A
include: a 14-bit current monitoring ADC, DAC-program-
mable current limit, and versatile quick port shutdown.
Advanced power management host software is available
under a no-cost license. PD discovery uses a proprietary
dual mode 4-point detection mechanism ensuring excellent
immunity from false PD detection. The LTC4266A includes
L
, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
LTPoE++ and QuikEval are trademarks of Linear Technology Corporation. All other trademarks
are the property of their respective owners.
an I
2
C serial interface operable up to 1MHz. Optional
I
2
C control is accessed on the DC1815A either with test
points or a 14-pin ribbon cable for DC590B QuikEval™
GUI operation.
The LTC4266A is configurable on the DC1815A 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 LTC4266A autonomously
detects a PD, turns power on to the port, and discon-
nects port power without the need for a microcontroller.
OUT
n
LEDs indicate that port power is present. A single
55V supply is required to power the DC1815A. A simple
LDO regulator circuit on the board powers the digital sup-
ply of the LTC4266A. A
SHDN
pushbutton for each port
shuts down the respective port and disables detection.
Pre-programmed masked shutdown ports are shut down
with the
MSD
pushbutton. A
RESET
pushbutton resets the
LTC4266A to its AUTO pin logic state. Ports shut down
with the
SHDN
or
MSD
pushbutton must be re-enabled
via I
2
C or a device reset with the AUTO pin high.
Design files for this circuit board are available at
Table 1. DC1815A Power Levels and Power Supply
DEMO BOARD
PSE CONTROLLER
MAX DELIVERED PD POWER
POWER SUPPLY*
DC1815A-A
LTC4266A-1
38.7W
300W
DC1815A-B
LTC4266A-2
52.7W
300W
DC1815A-C
LTC4266A-3
70W
420W
DC1815A-D
LTC4266A-4
90W
540W
*Recommended DC1815A power supply minimum to avoid drooping in a worst-case scenario with I
LIM
current at all four ports. Set the voltage between
54.75V to 57V for LTPoE++ compliance
