
ICS843156AKI REVISION B NOVEMBER 28, 2012
12
2012 Integrated Device Technology, Inc.
ICS843156I Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
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
to VCCO – 2V. For VCCO = 2.5V, the VCCO – 2V is very close to ground
level. The R3 in Figure 5B can be eliminated and the termination is
shown in Figure 5C.
Figure 5A. 2.5V LVPECL Driver Termination Example
Figure 5C. 2.5V LVPECL Driver Termination Example
Figure 5B. 2.5V LVPECL Driver Termination Example
2.5V LVPECL Driver
VCCO = 2.5V
2.5V
50
50
R1
250
R3
250
R2
62.5
R4
62.5
+
–
2.5V LVPECL Driver
VCCO = 2.5V
2.5V
50
50
R1
50
R2
50
+
–
2.5V LVPECL Driver
VCCO = 2.5V
2.5V
50
50
R1
50
R2
50
R3
18
+
–