LFXP15 Lattice Semiconductor, LFXP15 Datasheet - Page 43

• Manufacturer Part Number: LFXP15
• Description: LatticeXP Family
• Manufacturer: Lattice Semiconductor

Lattice Semiconductor
LVPECL
The LatticeXP devices support differential LVPECL standard. This standard is emulated using complementary
LVCMOS outputs in conjunction with a parallel resistor across the driver outputs. The LVPECL input standard is
supported by the LVDS differential input buffer. The scheme shown in Figure 3-3 is one possible solution for point-
to-point signals.
Figure 3-3. Differential LVPECL
Table 3-3. LVPECL DC Conditions
For further information on LVPECL, BLVDS and other differential interfaces please see details of additional techni-
cal documentation at the end of the data sheet.
RSDS
The LatticeXP devices support differential RSDS standard. This standard is emulated using complementary LVC-
MOS 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. Use LVDS25E mode with suggested resistors for RSDS operation. Resistor values in
Figure 3-4 are industry standard values for 1% resistors.
Z
R
R
R
V
V
V
V
Z
I
1. For input buffer, see LVDS table.
DC
OUT
BACK
OH
OL
OD
CM
P
S
T
Symbol
3.3V
3.3V
Output impedance
Driver parallel resistor
Driver series resistor
Receiver termination
Output high voltage
Output low voltage
Output differential voltage
Output common mode voltage
Back impedance
DC output current
Over Recommended Operating Conditions
R
R
1
S
S
Off-chip
= 100 ohms
= 100 ohms
Description
R
Transmission line, Zo = 100 ohm differential
P
= 187 ohms
3-12
DC and Switching Characteristics
Typical
2.03
1.27
0.76
1.65
85.7
12.7
100
187
100
100
R
T
= 100 ohms
LatticeXP Family Data Sheet
Units
ohms
ohms
ohms
ohms
ohms
mA
V
V
V
V
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