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Spartan-3A/3AN FPGA Starter Kit Board User Guide
UG334 (v1.1) June 19, 2008
Chapter 15:
Expansion Connectors
R
Differential I/O Connectors
The Spartan-3A/3AN Starter Kit board includes stake pin headers with excellent signal
integrity and matched impedance traces to demonstrate high-performance differential
I/O. Each differential pair supports approximately 600 Mbits per second (Mbps) data
rates. All I/O pairs support differential input termination (DIFF_TERM) as described in
the Spartan-3A and Spartan-3AN data sheets.
The board is primarily designed to support loopback operations using a standard 34-pin
socket-to-socket cable.
The two differential I/O headers, shown in
Figure 15-1, page 119
, consist of a 2x17 array of
stake pins arrange on 0.1-inch centers. The headers are not keyed. Ground pins are
interspersed with the signal pins for improved signal integrity over any attached cable.
Power is also supplied, via the nominally 3.3V rail, labeled VCCO_012. The power
connectors are for potential daughter cards that plug into the connector.
The J15 connector is primarily designed to transmit output data while the J2 connector is
primarily designed to receive input data. However, both headers are equally good at
transmitting differential data. The “Receive” header does have special provisions for
capturing the receive clock input.
The pin assignment for the J2 “Receive” connector appears in
Table 15-2
and in
Table 15-4
.
The FPGA ball assignment is listed in parentheses.
The pin assignment for the J15 “Transmit” connector appears in
Table 15-3
and in
Table 15-4
. The FPGA ball assignment is listed in parentheses.
Table 15-2:
Receive” Header (J2)
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
GND GND
RXN_0
(B4)
GND
RXN_1
(A5)
GND
RXN_2
(A6)
3.3V 3.3V 3.3V
RXN_3
(A8)
GND
RXN_4
(C10)
GND
RX_
CLK_N
(A11)
GND GND
GND GND
RXP_0
(A4)
GND
RXP_1
(B6)
GND
RXP_2
(A7)
3.3V 3.3V 3.3V
RXP_3
(A9)
GND
RXP_4
(A10)
GND
RX_
CLK_P
(A12)
GND GND
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
Table 15-3:
Transmit” Header (J15)
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
GND GND
TXN_0
(AA3)
GND
TXN_1
(AA4)
GND
TXN_2
(AB6)
3.3V 3.3V 3.3V
TXN_3
(AB7)
GND
TXN_4
(AB8)
GND
TX_
CLK_N
(AB10)
GND GND
GND GND
TXP_0
(AB2)
GND
TXP_1
(AB3)
GND
TXP_2
(AA6)
3.3V 3.3V 3.3V
TXP_3
(Y7)
GND
TXP_4
(AA8)
GND
TX_
CLK_P
(AA10)
GND GND
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33