DC and Switching Characteristics
LatticeECP/EC Family Data Sheet
Lattice Semiconductor
BLVDS
The LatticeECP/EC devices support BLVDS standard. This standard is emulated using complementary 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
Heavily loaded backplane, effective Zo ~ 45 to 90 ohms differential
2.5V
2.5V
2.5V
2.5V
80
45-90 ohms
45-90 ohms
80
80
80
80
80
80
. . .
+
-
+
-
-
-
2.5V
2.5V
2.5V
2.5V
Table 3-2. BLVDS DC Conditions1
Over Recommended Operating Conditions
Typical
Parameter
Description
Output impedance
Zo = 45 Zo = 90
Units
ohm
ohm
ohm
V
Z
100
45
100
90
OUT
R
R
Left end termination
Right end termination
Output high voltage
TLEFT
TRIGHT
OH
45
90
V
V
V
V
1.375
1.125
0.25
1.25
11.2
1.48
1.02
0.46
1.25
10.2
Output low voltage
V
OL
Output differential voltage
Output common mode voltage
DC output current
V
OD
V
CM
I
mA
DC
1. For input buffer, see LVDS table.
3-9
LATTICE [ LATTICE SEMICONDUCTOR ]
