ICS844S42I Datasheet, PDF (20/27 Pages) Integrated Device Technology – On-chip crystal oscillator for reference frequency generation

ICS844S42I Data Sheet
DUAL OUTPUT RF FREQUENCY SYNTHESIZER
Schematic Example
Figure 7 shows an example of ICS844S42I application schematic. In this example, the device is operated at V_DD = V_DDOA = V_DDOB = 3.3V.
The 18pF parallel resonant 16MHz crystal is used. The C1 and C2 = 22pF and are recommended for frequency accuracy. For differential board
layouts, the C1 and C2 may be slightly adjusted for optimizing frequency accuracy. Two examples of LVPECL terminations and one example
LVDS termination are shown in this schematic. Additional termination approaches are shown in the LVPECL Termination Application Note.
VDD
R1 ₁₀
C3
10u
VDDA
C4
0.01u
Q1
R4 ₃₃
LVCMOS_Driv er
C1
22pF
X1
16MHz, CL=18pF
Zo = 50
U1
58
PAD1
GND
1
VDD
nBY PASS
2
3
4
5
GND
nc
nBY PASS
nc
XTAL_IN
REF_CLK
GND
REF_SEL
6
7
8
9
VDD
REF_CLK
GND
REF_SEL
XTAL_OUT
10 ^XTAL_IN
nMR
LOCK_DT
LEV_SEL
11
12
13
14
XTAL_OUT
nMR
LOCK_DT
LEV_SEL
C2
VDD
VDD
22pF
Logic Control Input Examples
Set Logic
VDD _{Input to}
'1'
RU1
1K
Set Logic
VDD _{Input to}
'0'
RU2
Not Install
To Logic
Input
pins
RD1
Not Install
To Logic
Input
pins
RD2
1K
59 _PAD2
VDD
VDD
R10 R11
SP SP
J1
R12 0
5 SDA
4
3
2
R13 0
1 SCL
61
PAD4
42
nc
VDDOA
VDDOA
QA
41
40
39
38
nQA
GND
GND
GND
37
36
35
34
GND ₃₃
QB
nQB
VDDOB
VDDOB
32
31
30
29
nc
PAD3 ⁶⁰
VDDOA
VDDOB
VDD
VDDOA
(U1:40)
(U1:41)
VDDOB
(U1:30) (U1:31)
C5
0.1u
C6
0.1u
C7
0.1u
C8
0.1u
VDD
(U1:5) VDD (U1:14) (U1:15) (U1:28)
C9
0.1u
C10
0.1u
C11
0.1u
C12
0.1u
3.3V
R2
133
Zo = 50 Ohm
QA
R3
133
+
Zo = 50 Ohm
nQA
-
R5
R6
82.5
82.5
LVPECL
Termination
VCC = VCCOA= VCCOB = 3.3V
Zo = 50 Ohm
QB
+
Zo = 50 Ohm
nQB
-
R7
R8
50
50
Optional
R9
Y-Termination
50
Zo = 50 Ohm
Q
+
R14
Zo = 50 Ohm 100
nQ
-
LVDS
Termination_Option
Figure 7. ICS844S42I Schematic Example
ICS844S42BKI REVISION A FEBRUARY 21, 2012
20
©2012 Integrated Device Technology, Inc.