ECP2 Datasheet, PDF (67/386 Pages) Lattice Semiconductor – LatticeECP2/M Family Data Sheet

Lattice Semiconductor
DC and Switching Characteristics
LatticeECP2/M Family Data Sheet
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)
VCCIO = 2.5V
(+/-5%)
8mA
RS = 294 ohms
(+/-1%)
VCCIO = 2.5V
(+/-5%)
8mA
RS = 294 ohms
(+/-1%)
On-chip
Off-chip
R_P = 121 ohms
(+/-1%)
RT = 100 ohms
(+/-1%)
Transmission line,
Zo = 100 ohm differential
Off-chip
+
-
On-chip
Table 3-5. RSDS 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_P
Driver Parallel Resistor (+/-1%)
R_T
Receiver Termination (+/-1%)
V_OH
Output High Voltage
V_OL
Output Low Voltage
V_OD
Output Differential Voltage
V_CM
Output Common Mode Voltage
Z_BACK
Back Impedance
I_DC
DC Output Current
1. For input buffer, see LVDS table.
Typical
2.50
20
294
121
100
1.35
1.15
0.20
1.25
101.5
3.66
Units
V
Ω
Ω
Ω
Ω
V
V
V
V
Ω
mA
3-15