Lattice Semiconductor
DC and Switching Characteristics
LatticeSC/M Family Data Sheet
BLVDS
The LatticeSC devices support BLVDS standard. This standard is emulated using controlled impedance comple-
mentary LVCMOS outputs in conjunction with a parallel external resistor across the driver outputs. BLVDS is
intended for use when multi-drop and bi-directional multi-point differential signaling is required. The scheme shown
in Figure 3-2 is one possible solution for bi-directional multi-point differential signals.
Figure 3-2. BLVDS Multi-point Output Example
2.5V
100
Heavily loaded backplane, effective Zo ~ 45 to 90 ohms differential
45-90 ohms, +/- 1%
45-90 ohms, +/- 1%
2.5V
100
2.5V
100
+
-
...
2.5V
100
2.5V
100
+-
2.5V
100
2.5V
100
+-
2.5V
100
+
-
Table 3-2. BLVDS DC Conditions1
Over Recommended Operating Conditions
Symbol
Description
ZOUT
Output impedance
RTLEFT
Left end termination
RTRIGHT
Right end termination
VOH
Output high voltage
VOL
Output low voltage
VOD
Output differential voltage
VCM
Output common mode voltage
IDC
DC output current
1. For input buffer, see LVDS table.
Nominal
Zo = 45 Zo = 90
100
100
45
90
45
90
1.375
1.48
1.125
1.02
0.25
0.46
1.25
1.25
11.2
10.2
Units
ohm
ohm
ohm
V
V
V
V
mA
3-9