5P49V5943_17 Datasheet, PDF (27/33 Pages) Integrated Device Technology – Programmable Clock Generator

5P49V5943 DATASHEET
Termination for 2.5V LVPECL Outputs
Figures 2.5V LVPECL Driver Termination Example (1) and (2)
show examples of termination for 2.5V LVPECL driver. These
terminations are equivalent to terminating 50 to V_DDO – 2V.
For V_DDO = 2.5V, the V_DDO – 2V is very close to ground level.
The R3 in Figure 2.5V LVPECL Driver Termination Example
(3) can be eliminated and the termination is shown in example
(2).
VDDO = 2.5V
2.5V LVPECL
Driver
R1
250ohm
Zo=50ohm
2.5V
Zo=50ohm
R2
62.5ohm
R3
250ohm
2.5V
+
-
R4
62.5ohm
VDDO = 2.5V
2.5V
Zo=50ohm
Zo=50ohm
2.5V LVPECL
Driver
R1
50ohm
+
-
R2
50ohm
R3
18ohm
2.5V LVPECL Driver Termination Example (1)
VDDO = 2.5V
Zo=50ohm
Zo=50ohm
2.5V LVPECL
Driver
R1
50ohm
2.5V
+
-
R2
50ohm
2.5V LVPECL Driver Termination Example (3)
2.5V LVPECL Driver Termination Example (2)
MARCH 3, 2017
27
PROGRAMMABLE CLOCK GENERATOR