
ICS84314-02
700MHZ, CRYSTAL-TO-3.3V/2.5V LVPECL FREQUENCY SYNTHESIZER W/FANOUT BUFFER
IDT / ICS 3.3V/2.5V LVPECL FREQUENCY SYNTHESIZER
11
ICS84314AY-02 REV. A MARCH 24, 2009
Application Information
Recommendations for Unused Input and Output Pins
Inputs:
LVCMOS Control Pins
All control pins have internal pullups or pulldowns; additional
resistance is not required but can be added for additional
protection. A 1k
resistor can be used.
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 1k
resistor can be tied
from XTAL_IN to ground.
TEST_CLK Input
For applications not requiring the use of the test clock, it can be left
floating. Though not required, but for additional protection, a 1k
resistor can be tied from the TEST_CLK to ground.
Outputs:
LVPECL Outputs
The unused LVPECL output pair 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.
Power Supply Filtering Technique
As in any high speed analog circuitry, the power supply pins are
vulnerable to random noise. To achieve optimum jitter perform-
ance, power supply isolation is required. The ICS84314-02
provides separate power supplies to isolate any high switching
noise from the outputs to the internal PLL. VCC, VCCA and VCCO
should be individually connected to the power supply plane
through vias, and 0.01F bypass capacitors should be used for
each pin. Figure 2 illustrates this for a generic VCC pin and also
shows that VCCA requires that an additional 10 resistor along with
a 10
F bypass capacitor be connected to the V
CCA pin.
Figure 2. Power Supply Filtering
VCC
VCCA
3.3V
10
10F
.01F