ICS843246I Datasheet, PDF (10/17 Pages) Integrated Device Technology – FEMTOCLOCKS™ CRYSTAL-TO-3.3V LVPECL FREQUENCY SYNTHESIZER W/INTEGRATED FANOUT BUFFER

ICS843246I
FEMTOCLOCKS™ CRYSTAL-TO-3.3V LVPECL FREQUENCY SYNTHESIZER W/FANOUT BUFFER
TERMINATION FOR 2.5V LVPECL OUTPUT
Figure 4A and Figure 4B show examples of termination for 2.5V
LVPECL driver. These ter minations are equivalent to
terminating 50Ω to V - 2V. For V = 2.5V, the V - 2V is very
CC
CC
CC
VC C O=2. 5V
Zo = 50 Ohm
Zo = 50 Ohm
2,5V LVPECL
Driv er
2.5V
R1
R3
250
250
2.5V
+
-
R2
62.5
R4
62.5
close to ground level. The R3 in Figure 4B can be eliminated
and the termination is shown in Figure 4C.
VCCO=2.5V
Zo = 50 Ohm
Zo = 50 Ohm
2,5V LVPECL
Driv er
2.5V
+
-
R1
R2
50
50
R3
18
FIGURE 4A. 2.5V LVPECL DRIVER TERMINATION EXAMPLE
FIGURE 4B. 2.5V LVPECL DRIVER TERMINATION EXAMPLE
VCCO=2.5V
Zo = 50 Ohm
Zo = 50 Ohm
2,5V LVPECL
Driv er
2.5V
+
-
R1
R2
50
50
FIGURE 4C. 2.5V LVPECL DRIVER TERMINATION EXAMPLE
IDT^™ / ICS^™ 3.3V LVPECL FREQUENCY SYNTHESIZER
10
ICS843246BGI REV. A AUGUST 2, 2007