ICS8S89874I Datasheet, PDF (12/19 Pages) Integrated Device Technology – 1:2 Differential-to-LVPECL Buffer/Divider

ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
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 50Ω
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.
V_CC = 2.5V
50Ω
50Ω
2.5V LVPECL Driver
2.5V
R1
250Ω
R3
250Ω
2.5V
+
–
R2
62.5Ω
R4
62.5Ω
VCC = 2.5V
50Ω
50Ω
2.5V LVPECL Driver
2.5V
+
–
R1
R2
50Ω
50Ω
R3
18Ω
Figure 5A. 2.5V LVPECL Driver Termination Example
Figure 5B. 2.5V LVPECL Driver Termination Example
V_CC = 2.5V
50Ω
50Ω
2.5V LVPECL Driver
2.5V
+
–
R1
R2
50Ω
50Ω
Figure 5C. 2.5V LVPECL Driver Termination Example
ICS8S89874BKI REVISION A OCTOBER 22, 2010
12
©2010 Integrated Device Technology, Inc.