XP2 Datasheet, PDF (54/92 Pages) Lattice Semiconductor – LatticeXP2 Family Data Sheet

Lattice Semiconductor
DC and Switching Characteristics
LatticeXP2 Family Data Sheet
BLVDS
The LatticeXP2 devices support the 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
2.5V
16mA
Heavily loaded backplane, effective Zo ~ 45 to 90 ohms differential
R_S =
90 ohms
R_S =
90 ohms
2.5V
16mA
2.5V
16mA
+
-
45-90
ohms ^RTL
R_S = 90 ohms
R_S = 90 ohms
R_S =
90 ohms
45-90
ohms
R_TR
R_S =
. . . ^{90 ohms}
R_S =
90 ohms
R_S =
90 ohms
2.5V
16mA
-
-
2.5V
2.5V
2.5V
2.5V
16mA
16mA
16mA
16mA
Table 3-2. BLVDS DC Conditions¹
Over Recommended Operating Conditions
Parameter
Description
V_CCIO
Output Driver Supply (+/- 5%)
Z_OUT
Driver Impedance
R_S
Driver Series Resistor (+/- 1%)
R_TLEFT
Driver Parallel Resistor (+/- 1%)
R_TRIGHT
Receiver Termination (+/- 1%)
V_OH
Output High Voltage (After R1)
V_OL
Output Low Voltage (After R1)
V_OD
Output Differential Voltage (After R1)
V_CM
Output Common Mode Voltage
I_DC
DC Output Current
1. For input buffer, see LVDS table.
Typical
Zo = 45Ω Zo = 45Ω
2.50
2.50
10.00
10.00
90.00
90.00
45.00
90.00
45.00
90.00
1.38
1.48
1.12
1.02
0.25
0.46
1.25
1.25
11.24
10.20
Units
V
Ω
Ω
Ω
Ω
V
V
V
V
mA
3-10