ICS840004I-01 Datasheet, PDF (8/10 Pages) Integrated Circuit Systems – FEMTOCLOCKS™ CRYSTAL-TO LVCMOS/LVTTL FREQUENCY SYNTHESIZER

Integrated
Circuit
Systems, Inc.
PRELIMINARY
ICS840004I-01
FEMTOCLOCKS™ CRYSTAL-TO-
LVCMOS/LVTTL FREQUENCY SYNTHESIZER
LAYOUT GUIDELINE
Figure 3 shows a schematic example of the ICS840004I-01. An
example of LVCMOS termination is shown in this schematic.
Additional LVCMOS termination approaches are shown in the
LVCMOS Termination Application Note. In this example, an 18pF
parallel resonant 25MHz crystal is used. The C1=22pF and
C2=22pF are recommended for frequency accuracy. For differ-
ent board layout, the C1 and C2 may be slightly adjusted for
optimizing frequency accuracy. 1KΩ pullup or pulldown resis-
tors can be used for the logic control input pins.
Logic Control Input Examples
Set Logic
VDD
Input to
'1'
RU1
1K
Set Logic
VD D
Input to
'0'
RU2
Not Install
VDD=3.3V
VDDO=3.3V
To Logic
Input
pins
RD1
Not Install
To Logic
Input
pins
RD2
1K
VDD
VD DA
R2
C3
10 10uF
VDD
C4
0. 01u
VD D
C6
0. 1u
U1
1
2
F_SEL0
3
4
nc
nXTAL_SEL
5
6
7
TEST_CLK
OE
MR
8 ^nPLL_SEL
9 ^VDDA
10
nc
VD D
I C S840004 i-01
F_SEL1
20
19
GND
Q0
18
17
Q1
VD DO
Q2
16
15
14
Q3 ₁₃
GND ₁₂
XTAL_IN
XTAL_OU T
11
XTAL_OU T
C2
22pF
X1
XTAL_IN
If not using the crystal input, it can be left floating.
C1
22pF
For additional protection the XTAL_IN pin can be
tied to ground.
R3
36
Zo = 50 Ohm
VDD O
LVC MOS
C5
0. 1u
VD D
R5
100
Zo = 50 Ohm
R4
100
LVC MOS
Optional Termination
Unused outputs can be left floating. There should be
no trace attached to unused outputs. Device
characterized and specification limits set with all
outputs terminated.
FIGURE 3. ICS840004I-01 SCHEMATIC EXAMPLE
RELIABILITY INFORMATION
TABLE 6. θ_JAVS. AIR FLOW TABLE FOR 20 LEAD TSSOP
θ_JA by Velocity (Linear Feet per Minute)
Single-Layer PCB, JEDEC Standard Test Boards
Multi-Layer PCB, JEDEC Standard Test Boards
0
114.5°C/W
73.2°C/W
200
98.0°C/W
66.6°C/W
500
88.0°C/W
63.5°C/W
NOTE: Most modern PCB designs use multi-layered boards.The data in the second row pertains to most designs.
TRANSISTOR COUNT
The transistor count for ICS840004I-01 is: TBD
840004AGI-01
www.icst.com/products/hiperclocks.html
8
REV. A JUNE 28, 2005