IDT / ICS 3.3V, 2.5V LVPECL CLOCK GENERATOR
9
ICS843031AG-01 REV. A NOVEMBER 11, 2008
ICS843031-01
FEMTOCLOCKS CRYSTAL-TO-3.3V, 2.5V LVPECL CLOCK GENERATOR
TERMINATION FOR 2.5V LVPECL OUTPUTS
Figure 5A and Figure 5B show examples of termination for 2.5V
LVPECL driver. These terminations are equivalent to terminating
50
Ω to V
CC
- 2V. For V
CC
= 2.5V, the V
CC
- 2V is very close to ground
level. The R3 in Figure 5B can be eliminated and the termination
is shown in
Figure 5C.
FIGURE 5C. 2.5V LVPECL TERMINATION EXAMPLE
FIGURE 5B. 2.5V LVPECL DRIVER TERMINATION EXAMPLE
FIGURE 5A. 2.5V LVPECL DRIVER TERMINATION EXAMPLE
R2
62.5
Zo = 50 Ohm
R1
250
+
-
2.5V
2,5V LVPECL
Driv er
R4
62.5
R3
250
Zo = 50 Ohm
2.5V
VCC=2.5V
R1
50
R3
18
Zo = 50 Ohm
+
-
2,5V LVPECL
Driv er
VCC=2.5V
2.5V
R2
50
2,5V LVPECL
Driv er
VCC=2.5V
R1
50
R2
50
2.5V
Zo = 50 Ohm
+
-