ICS843S1333 Datasheet, PDF (8/13 Pages) Integrated Device Technology – CRYSTAL-TO-3.3V LVPECL CLOCK SYNTHESIZER

ICS843S1333
CRYSTAL-TO-3.3V LVPECL CLOCK SYNTHESIZER
Schematic Example
Figure 5 shows an example of the ICS843S133 application
schematic. In this example, the device is operated at VCC = 3.3V.
The 18pF parallel resonant 20MHz crystal is used. The C1 = 14pF
and C2 = 14pF are recommended for frequency accuracy. For
different board layout, the C1 and C2 may be slightly adjusted for
optimizing frequency accuracy. Two examples of LVPECL
termination are shown in this schematic. Additional termination
approaches are shown in the LVPECL Termination Application
Note.
VCC
R1
10 C4
10uF
VCCA
C5
0.01u
XTAL_OUT
XTAL_IN
U1
1
2
3
VCCA
VEE
4 ^XTAL_OUT
XTAL_IN
ICS843S1333
C2
14pF
X1
18pF
20MHz
C1
14pF
Logic Control Input Examples
Set Logic
VCC _{Input to}
'1'
RU1
1K
Set Logic
VCC _{Input to}
'0'
RU2
Not Install
To Logic
Input
pins
RD1
Not Install
To Logic
Input
pins
RD2
1K
VCC
VCC
C3
0.01u
VCC
Q
8
7
6
Q
nQ _{5 OE}
nQ
OE
VCC=3.3V
3.3V
R2
R3
133
133
Zo = 50 Ohm
+
Zo = 50 Ohm
-
R4
R5
82.5
82.5
Zo = 50 Ohm
Zo = 50 Ohm
R6
50
+
-
R7
50
Optional
R8
Y-Termination
50
Figure 5. ICS843S1333 Schematic Example
IDT™ / ICS™ 3.3V LVPECL CLOCK SYNTHESIZER
8
ICS843S1333CG REV. A AUGUST 28, 2008