
Device Architecture
2-214
Revision 4
LVPECL
Low-Voltage Positive Emitter-Coupled Logic (LVPECL) is another differential I/O standard. It requires
that one data bit be carried through two signal lines. Like LVDS, two pins are needed. It also requires
external resistor termination.
The full implementation of the LVDS transmitter and receiver is shown in an example in
Figure 2-136.
The building blocks of the LVPECL transmitter–receiver are one transmitter macro, one receiver macro,
three board resistors at the transmitter end, and one resistor at the receiver end. The values for the three
driver resistors are different from those used in the LVDS implementation because the output standard
specifications are different.
Timing Characteristics
Figure 2-136 LVPECL Circuit Diagram and Board-Level Implementation
Table 2-171 Minimum and Maximum DC Input and Output Levels
DC Parameter
Description
Min.
Max.
Min.
Max.
Min.
Max.
Units
VCCI
Supply Voltage
3.0
3.3
3.6
V
VOL
Output Low Voltage
0.96
1.27
1.06
1.43
1.30
1.57
V
VOH
Output High Voltage
1.8
2.11
1.92
2.28
2.13
2.41
V
VIL, VIH
Input Low, Input High Voltages
0
3.6
0
3.6
0
3.6
V
VODIFF
Differential Output Voltage
0.625
0.97
0.625
0.97
0.625
0.97
V
VOCM
Output Common Mode Voltage
1.762
1.98
1.762
1.98
1.762
1.98
V
VICM
Input Common Mode Voltage
1.01
2.57
1.01
2.57
1.01
2.57
V
VIDIFF
Input Differential Voltage
300
mV
Table 2-172 AC Waveforms, Measuring Points, and Capacitive Loads
Input Low (V)
Input High (V)
Measuring Point* (V)
VREF (typ.) (V)
1.64
1.94
Cross point
–
187 W
100
ZO = 50
ZO = 50
100
100
+
–
P
N
P
N
INBUF_LVPECL
OUTBUF_LVPECL
FPGA
Bourns Part Number: CAT16-PC4F12
Table 2-173 LVPECL
Commercial Temperature Range Conditions: TJ = 70°C, Worst-Case VCC = 1.425 V,
Worst-Case VCCI = 3.0 V
Applicable to Pro I/Os
Speed Grade
tDOUT
tDP
tDIN
tPY
Units
Std.
0.66
2.14
0.04
1.63
ns
–1
0.56
1.82
0.04
1.39
ns
–2
0.49
1.60
0.03
1.22
ns
Note: For the derating values at specific junction temperature and voltage supply levels, refer to Table 3-7 on