ICS843001I-23 Datasheet, PDF (15/24 Pages) Integrated Circuit Systems – FEMTOCLOCKS™ CRYSTAL-TO-3.3V LVPECL/LVCMOS FREQUENCY SYNTHESIZER

ICS843001I-23 Data Sheet
FEMTOCLOCK^® CRYSTAL/LVCMOS-TO-LVPECL/LVCMOS FREQUENCY SYNTHESIZER
Termination for 2.5V LVPECL Outputs
Figure 3A and Figure 3B show examples of termination for 2.5V
LVPECL driver. These terminations are equivalent to terminating
50Ω to V_CCO – 2V. For V_CCO = 2.5V, the V_CCO – 2V is very close to
ground level. The R3 in Figure 3B can be eliminated and the
termination is shown in Figure 3C.
V_CCO = 2.5V
50Ω
50Ω
2.5V LVPECL Driver
2.5V
R1
R3
250
250
2.5V
+
–
R2
R4
62.5
62.5
Figure 3A. 2.5V LVPECL Driver Termination Example
VCCO = 2.5V
50Ω
50Ω
2.5V LVPECL Driver
2.5V
+
–
R1
R2
50
50
R3
18
Figure 3B. 2.5V LVPECL Driver Termination Example
V_CCO = 2.5V
50Ω
50Ω
2.5V LVPECL Driver
2.5V
+
–
R1
R2
50
50
Figure 3C. 2.5V LVPECL Driver Termination Example
ICS843001CGI-23 REVISION A OCTOBER 4, 2011
15
©2011 Integrated Device Technology, Inc.