Linear Technology DC1680A, Демонстрационное руководство

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dc1840afb
DEMO MANUAL DC1840A
Demonstration circuit 1680a operation
Demonstration circuit 1680A is a 12-Port, IEEE802.3at
Type 1 and Type 2 PoE PSE mother board. This board
accepts various PSE daughter cards featuring Linear
Technology PSE controllers. The DC1680A is capable of
powering up to 12 PDs.
Daughter Card Insertion Precautions
When inserting or removing the daughter card into the
DC1840A, 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.
V
EE
Supply
Connect a power supply for V
EE
with the positive rail to POS
and negative rail to NEG as shown in Figure 3 of the Quick
Start Procedure. Set the voltage within the range in Table 1
depending on whether the application is a Type 1 or Type 2.
Choose a power supply rating and set the current limit
high enough to provide power for the maximum number of
PDs connected and to meet each PD power requirements.
Table 1. DC1680A V
EE
Power Range for Type 1 and Type 2 PSEs
PSE TYPE
V
EE
SUPPLY
RANGE
MAX DELIVERED
PORT POWER
POWER
SUPPLY*
Type 1 45V to 57V 13W 300W
Type 2 51V to 57V 25.5W 600W
*Recommended DC1840A power supply minimum to avoid dropping in
a worst-case scenario with I
LIM
current at all 12 ports.
PD Connection
PDs are connected using an Ethernet cable to any of the
12 ports at the 2×6, RJ45 connector J4 on the DC1680A
(Figure 3). J4 has an integrated Ethernet transformer and
common mode termination for each port. Test points for
port outputs OUT1 through OUT12 are provided.
DC1680A USER FEATURES
Refer to Figure 12 and Figure 13 for the following user
features.
Onboard 3.3V Supply
The DC1680A has an onboard V
DD33
digital supply gener-
ated from the V
EE
supply. V
DD33
is tied to AGND, and DGND
is a negative voltage referenced to AGND. If an external
3.3V supply is to be used, contact Linear Technology Ap-
plications for proper connection.
V
EE
and V
DD33
LED Indicators
LEDs for V
EE
and V
DD33
indicate if voltage is present at
these supplies. Verify these LEDs are off before inserting
or removing the daughter card.
Digital Connections
The DC1680A has connections for I
2
C control from a
host controller. The DC590 is optionally connected to
the DC1680A at J5 through a 14-pin ribbon cable. The
QuikEval software will automatically detect the DC1680A
and open the LTC4271 GUI. Refer to the LTC4271 PSE
Demo Software User Manual document for instructions
on using the GUI. A second 14-pin ribbon cable can be
connected to J6 for I
2
C expansion to another DC1680A
board with slight board modifications. Contact Linear
Technology Applications for instructions.
Digital test points include SCL, SDA, DGND,
INT , MSD ,
and RESET . I
2
C address pin AD6, AD3, and AD2 are set
with a 3-bit switch SW3.
Midspan PSE
The DC1840A can be configured as a midspan PSE.
Upstream switch data comes in to J3. Data and PoE go
out to a PD at J4. Set both MID and AUTO pins logic high.