Demonstration Circuit 2683A Mother Board - Analog Devices DC2685A Demo Manual

DEMONSTRATION CIRCUIT 2683A MOTHER BOARD

Demonstration circuit 2683A is a 4-Port, 2-channels per
port IEEE 802.3bt PoE PSE motherboard. This board
accepts an IEEE 802.3bt four port PSE daughter card
featuring the LTC4292/LTC4291 chipset.
Daughter Card Insertion Precautions
When inserting or removing the daughter card into the
DC2683A motherboard, verify all supplies and LEDs are
off. Push the card straight down for insertion or pull
straight up for removal to avoid bending the connector
pins. Follow the instructions in the Quick Start Procedure
for alignment.
Main V PoE Supply
EE
The V supply is the main PoE supply and connects to
EE
the DC2683A with the positive rail to AGND (+) and the
negative rail to V (–) as shown in Figure 3 of the Quick
EE
Start Procedure. The voltage must be within the range
shown in Table 3 depending on the application PSE type.
For full load testing at each port, choose a power supply
that is set with a current limit higher than the maximum
allowed output power at each port.
Onboard 3.3V Supply
The DC2683A motherboard has an onboard (non-isolated)
3.3V LDO for the LTC4292/LTC4291 V
generated from the V supply. This onboard logic supply
EE
is for demonstration purpose to allow for a single sup-
ply connection to the DC2685A kit. DGND is tied to V
through shunt resistor R42. To isolate the logic supply
from the PoE supply, remove R42 and R41 and apply an
external isolated 3.3V supply across V
the DC2685A kit is connected in parallel for multi-quad
port evaluation, verify all ground connections are correct
before applying power.
LED Indicators
V LED (D5) and V LED (D7) indicate if a voltage is
EE DD
present at these supplies. Verify these LEDs are off before
inserting or removing the daughter card.
Each pairset channel (2 per port) has a respective OUTnM
LED to indicate if the channel is powered on with PoE.
DEMO MANUAL DC2685A
The INT LED (D6) indicates if the interrupt line is pulled
low by the daughter card. When the interrupt is cleared
(high) via I
Digital Connections
The DC590 (USB to I
to the DC2683A at J6 through a 14-pin ribbon cable. The
QuikEval software must be previously installed. When
QuikEval is opened, the software will automatically detect
the DC2685A kit and open the LTC4291 GUI.
2
I C address pins AD3 and AD2 are set with a 2-bit switch
SW3 on the DC2683A. Refer to Table 4 for setting the
individual I
Turret digital test points for SCL, SDA, DGND, INT, MSD,
and RESET are provided on the DC2683A.
RJ45 Connections
PDs are connected using an Ethernet cable to any of the
bottom row ports at 2 × 4, RJ45 connector J1 on the
DC2683A. Test points for each channel output OUT1A
through OUT4B, are provided. Optionally, an Ethernet data
source may be connected with an Ethernet cable to any of
the top row ports at J1.
MSD and RESET Pushbuttons
supply which is
DD
Pushbutton switch SW1, when pressed, pulls the RESET
pin of the daughter card logic low. The PSE controller
is then held inactive with all ports off. When SW1 is
EE
released, RESET is pulled high, and the PSE returns to
the AUTO pin reset state.
and DGND. If
Pushbutton switch SW2, when pressed, pulls the mask-
DD
able shutdown input (MSD) pin of the daughter card logic
low. When pressed, all ports that have their corresponding
mask bit set in the mconfig register of the PSE controller
will be shutdown. These ports must then be manually
re-enabled via I
2
C interrupt servicing, the LED is turned off.
2
C) controller board is connected
2
C address for each DC2685A kit.
2
C or by resetting the PSE.
UG-1339 Rev 0
7