ICS8442AYILF View Datasheet(PDF) - Integrated Circuit Systems
Part Name
Description
MFG CO.
ICS8442AYILF
Integrated Circuit Systems
'ICS8442AYILF' PDF : 15 Pages View PDF
Integrated
Circuit
Systems, Inc.
ICS8442I
700MHZ, CRYSTAL OSCILLATOR-TO-DIFFERENTIAL
LVDS FREQUENCY SYNTHESIZER
CRYSTAL INPUT INTERFACE
A crystal can be characterized for either series or parallel mode
operation. The ICS8442I has a built-in crystal oscillator circuit.
This interface can accept either a series or parallel crystal without
additional components and generate frequencies with accuracy
suitable for most applications. Additional accuracy can be
achieved by adding two small capacitors C1 and C2 as shown in
Figure 3. Typical results using parallel 18pF crystals are shown
in Table 10.
X1
18pF Parallel Crystal
XTAL_IN
C1
18p
XTAL_OUT
C2
22p
Figure 3. CRYSTAL INPUt INTERFACE
LVDS DRIVER TERMINATION
A general LVDS interface is shown in Figure 4. In a 100Ω differ-
ential transmission line environment, LVDS drivers require a
matched load termination of 100Ω across near the receiver in-
put. For a multiple LVDS outputs buffer, if only partial outputs
are used, it is recommended to terminate the un-used outputs.
3.3V
Zo = 50 Ohm
3.3V
LVDS_DRIVER
R1
100
Zo = 50 Ohm
CLK
nCLK
HiPerClockS
100Ω Differential Transmission Line
FIGURE 4. TYPICAL LVDS DRIVER TERMINATION
DIFFERENTIAL DUTY CYCLE IMPROVEMENT
The schematic below is recommended for applications using the
÷1 output configuration for improving the differential duty cycle.
Vcc = 3.3V
LVDS Driv er
Zo = 50
Zo = 50
C1
R1 .1uf
100
C2
.1uf
R2
R4
1.3k 1.3k
+
-
R3
R5 Receiv er_dif
800
800
8442AYI
FIGURE 5. DIFFERENTIAL DUTY CYCLE IMPROVEMENT
www.icst.com/products/hiperclocks.html
9
REV. C MAY 10, 2005
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