ICS8535I-31 Datasheet, PDF (8/15 Pages) Integrated Device Technology – LOW SKEW, 1-TO-4, CRYSTAL OSCILLATOR/LVCMOS-TO-3.3V LVPECL FANOUT BUFFER

ICS8535I-31
LOW SKEW, 1-TO-4, CRYSTAL OSCILLATOR/LVCMOS-TO-3.3V LVPECL FANOUT BUFFER
Application Information
Recommendations for Unused Input and Output Pins
Inputs:
Crystal Inputs
For applications not requiring the use of the crystal oscillator input,
both XTAL_IN and XTAL_OUT can be left floating. Though not
required, but for additional protection, a 1kW resistor can be tied
from XTAL_IN to ground.
CLK Input
For applications not requiring the use of a clock input, it can be left
floating. Though not required, but for additional protection, a 1kΩ
resistor can be tied from the CLK to ground.
LVCMOS Control Pins
All control pins have internal pull-ups or pull-downs; additional
resistance is not required but can be added for additional
protection. A 1kΩ resistor can be used.
Outputs:
LVPECL Outputs
All unused LVPECL outputs can be left floating. We recommend
that there is no trace attached. Both sides of the differential output
pair should either be left floating or terminated.
Crystal Input Interface
The ICS8535I-31 has been characterized with 18pF
parallel resonant crystals. The capacitor values shown in
Figure 2 below were determined using an 18pF parallel resonant
crystal and were chosen to minimize the ppm error.
.
These same capacitor values will tune any 18pF parallel resonant
crystal over the frequency range and other parameters specified in
this data sheet. The optimum C1 and C2 values can be slightly
adjusted for different board layouts
X1
18pF Parallel Crystal
XTAL_IN
C1
XTAL_OUT
C2
Figure 2. Crystal Input Interface
IDT™ / ICS™3.3V LVPECL FANOUT BUFFER
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ICS8535AGI-31 REV. A AUGUST 16, 2007