DC and Switching Characteristics
LatticeECP2/M Family Data Sheet
Lattice Semiconductor
RSDS
The LatticeECP2/M devices support differential RSDS standard. This standard is emulated using complementary
LVCMOS outputs in conjunction with a parallel resistor across the driver outputs. The RSDS input standard is sup-
ported by the LVDS differential input buffer. The scheme shown in Figure 3-4 is one possible solution for RSDS
standard implementation. Resistor values in Figure 3-4 are industry standard values for 1% resistors.
Figure 3-4. RSDS (Reduced Swing Differential Signaling)
V
= 2.5V
(+/-5%)
CCIO
R
S
= 294 ohms
(+/-1%)
8mA
+
-
V
= 2.5V
(+/-5%)
R
P
= 121 ohms
(+/-1%)
R = 100 ohms
T
CCIO
(+/-1%)
R
S
= 294 ohms
(+/-1%)
8mA
On-chip
Transmission line,
Zo = 100 ohm differential
Off-chip
Off-chip
On-chip
Table 3-5. RSDS DC Conditions1
Over Recommended Operating Conditions
Parameter
Description
Typical
2.50
20
Units
V
V
Output Driver Supply (+/-5%)
Driver Impedance
CCIO
OUT
Z
Ω
R
R
R
Driver Series Resistor (+/-1%)
Driver Parallel Resistor (+/-1%)
Receiver Termination (+/-1%)
Output High Voltage
294
Ω
S
121
Ω
P
100
Ω
T
V
V
V
V
1.35
1.15
0.20
1.25
101.5
3.66
V
OH
OL
OD
CM
BACK
Output Low Voltage
V
Output Differential Voltage
Output Common Mode Voltage
Back Impedance
V
V
Z
Ω
I
DC Output Current
mA
DC
1. For input buffer, see LVDS table.
3-15
LATTICE [ LATTICE SEMICONDUCTOR ]
