
ICS844004AKI-104 REVISION A DECEMBER 15, 2010
12
2010 Integrated Device Technology, Inc.
ICS844004I-104 Data Sheet
FEMTOCLOCK CRYSTAL-TO-LVDS FREQUENCY SYNTHESIZER
Schematic Example
Figure 6 shows an example of ICS844004I-104 application
schematic. In this example, the device is operated at VDD = VDDO =
3.3V. The 18pF parallel resonant 25MHz crystal is used. The C1 =
33pF and C2 = 27pF are recommended for frequency accuracy. For
different board layouts, the C1 and C2 may be slightly adjusted for
optimizing frequency accuracy. Two examples of LVDS for receiver
without built-in termination are shown in this schematic.
Figure 6. ICS844004I-104 Schematic Layout
R1
33
nQ0
Alternate
LVDS
Termination
C3
0.1uF
nQ
0
R3
50
To Logic
Input
pins
C4
0.1uF
C8
.1uf
nPLL_SEL
Logic Control Input Examples
R2
100
Set Logic
Input to
'1'
VDDA
U1
ICS844004-104
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16
17
18
19
20
21
22
23
24
32 31 30 29 28 27 26 25
Q0
nQ0
MR
nPLL_SEL
nc
VD
D
A
F
_
SEL
0
VD
D
F
_
SEL
1
XT
AL
_O
U
T
XT
AL
_I
N
nc nc
GND
REF_CLK
nXTAL_SEL
nc
GND
nQ3
Q3
VD
D
O Q1
nQ
1
nc nc
nQ
2
Q2
VD
D
O
R1
10
VDD=3.3V
RD2
1K
REF_CLK
Zo = 50 Ohm
RU2
Not Install
R4
50
C1
33pF
nQ3
Q3
Zo = 50 Ohm
MR
VDD
nXTAL_SEL
VDD
Q3
Zo = 50 Ohm
nQ3
RD1
Not Install
Zo = 50 Ohm
X1
25MHz
Q1
Driv er_LVCMOS
RU1
1K
F_SEL0
C5
0.01u
To Logic
Input
pins
VDDO
VDD
Q0
C2
27pF
+
-
Set Logic
Input to
'0'
VDDO
+
-
C7
0.1uF
VDD
C6
10uF
F_SEL1
1 8 p F
Q0
VDDO=3.3V
Zo = 50