a3p1000-1pqg208m Actel Corporation, a3p1000-1pqg208m Datasheet - Page 94

• Manufacturer Part Number: a3p1000-1pqg208m
• Description: Fpga Proasic 3 Family 1m Gates 130nm Cmos Technology 1.5v 208-pin Pqfp
• Manufacturer: Actel Corporation

Military ProASIC3/EL DC and Switching Characteristics
Figure 2-25 • B-LVDS/M-LVDS Multipoint Application Using LVDS I/O Buffers
2- 80
R
T
Z
Z
Z
stub
0
0
Receiver
+
R
R
S
B-LVDS/M-LVDS
Bus LVDS (B-LVDS) and Multipoint LVDS (M-LVDS) specifications extend the existing LVDS standard to
high-performance multipoint bus applications. Multidrop and multipoint bus configurations may contain
any combination of drivers, receivers, and transceivers. Actel LVDS drivers provide the higher drive
current required by B-LVDS and M-LVDS to accommodate the loading. The drivers require series
terminations for better signal quality and to control voltage swing. Termination is also required at both
ends of the bus since the driver can be located anywhere on the bus. These configurations can be
implemented using the TRIBUF_LVDS and BIBUF_LVDS macros along with appropriate terminations.
Multipoint designs using Actel LVDS macros can achieve up to 200 MHz with a maximum of 20 loads. A
sample application is given in
section in
Example: For a bus consisting of 20 equidistant loads, the following terminations provide the required
differential voltage, in worst-case Industrial operating conditions, at the farthest receiver: R
R
-
T
EN
R
Z
= 70 Ω, given Z
S
stub
Z
Z
Table 2-142 on page
Z
0
0
stub
Transceiver
+
R
T
S
0
-
= 50 Ω (2") and Z
EN
R
Z
stub
S
Z
Z
Z
0
0
Figure
stub
2-78.
Driver
+
R
D
S
2-25. The input and output buffer delays are available in the LVDS
stub
-
EN
R
Z
S
stub
= 50 Ω (~1.5").
R e visio n 0
Z
Z
Z
0
0
stub
Receiver
+
R
R
S
-
EN
R
Z
S
stub
...
Z
Z
0
0
Transceiver
+
R
T
S
-
EN
R
S
S
BIBUF_LVDS
= 60 Ω and
Z
Z
0
0
R
T