afs600 Actel Corporation, afs600 Datasheet - Page 204

• Manufacturer Part Number: afs600
• Description: Actel Fusion Programmable System Chips Mixed-signal Family With Optional Arm Support
• Manufacturer: Actel Corporation

Table 2-167 • LVDS
BLVDS/M-LVDS
Bus LVDS (BLVDS) and Multipoint LVDS (M-LVDS)
specifications extend the existing LVDS standard to high-
performance multipoint bus applications. Multidrop and
multipoint
combination of drivers, receivers, and transceivers. Actel
LVDS drivers provide the higher drive current required by
BLVDS and M-LVDS to accommodate the loading. The
driver requires 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
Figure 2-127 • BLVDS/M-LVDS Multipoint Application Using LVDS I/O Buffers
2 -1 9 0
Speed Grade
Std.
–1
–2
Note: For the derating values at specific junction temperature and voltage supply levels, refer to
Actel Fusion Programmable System Chips
Timing Characteristics
R
T
Z
Z
Z
stub
0
0
Receiver
+
Commercial-Case Conditions: T
Applicable to Pro I/Os
bus
R
R
S
-
EN
R
Z
S
stub
configurations
Z
Z
Z
0
0
stub
Transceiver
+
R
T
S
-
EN
R
Z
can
S
stub
J
Z
Z
contain
= 70°C, Worst-Case V
Z
0
0
stub
t
0.66
0.56
0.49
DOUT
Driver
+
R
D
S
A d v a n c e d v 1 . 4
-
EN
any
R
Z
S
stub
be implemented using 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
output buffer delays are available in the LVDS section in
Table 2-165 on page
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
Z
Z
Z
Z
0
2.10
1.79
1.57
0
0
t
stub
CC
DP
= 50 Ω (2") and Z
Receiver
= 1.425 V, Worst-Case V
+
R
R
S
-
EN
R
Z
S
stub
t
0.04
0.04
0.03
DIN
...
stub
2-189.
Table 3-7 on page
= 50 Ω (~1.5").
S
Z
Z
Figure
= 60 Ω and R
0
0
CCI
Transceiver
= 2.3 V
+
1.82
1.55
1.36
t
R
T
2-127. The input and
PY
S
-
EN
R
S
3-9.
T
= 70 Ω, given
BIBUF_LVDS
Z
Z
0
0
Units
ns
ns
ns
R
T