ICS84330-03 Datasheet, PDF (11/20 Pages) Integrated Circuit Systems – 700MHZ, LOW JITTER, CRYSTAL-TO-3.3V DIFFERENTIAL LVPECL FREQUENCY SYNTHESIZER

Integrated
Circuit
Systems, Inc.
ICS84330-03
700MHZ, LOW JITTER, CRYSTAL-TO-3.3V
DIFFERENTIAL LVPECL FREQUENCY SYNTHESIZER
APPLICATION INFORMATION
POWER SUPPLY FILTERING TECHNIQUES
As in any high speed analog circuitry, the power supply pins
are vulnerable to random noise. The ICS84330-03 provides
separate power supplies to isolate any high switching
noise from the outputs to the internal PLL. V_CC and V_CCA
should be individually connected to the power supply
plane through vias, and bypass capacitors should be
used for each pin. To achieve optimum jitter performance,
power supply isolation is required. Figure 2 illustrates how
a 10Ω resistor along with a 10μF and a .01μF bypass
capacitor should be connected to each V_CCA pin. The 10Ω
resistor can also be replaced by a ferrite bead.
V
CC
V_CCA
3.3V
.01μF 10Ω
.01μF 10μF
FIGURE 2. POWER SUPPLY FILTERING
RECOMMENDATIONS FOR UNUSED INPUT AND OUTPUT PINS
INPUTS:
SELECT PINS:
All select pins have internal pull-ups and pull-downs;
additional resistance is not required but can be added for
additional protection. A 1kΩ resistor can be used.
OUTPUTS:
LVPECL OUTPUT
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 ICS84330-03 has been characterized with 18pF paral-
lel resonant crystals. The capacitor values, C1 and C2,
shown in Figure 3 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.
84330AY-03
X1
18pF Parallel Cry stal
XTAL_IN
C1
22p
XTAL_OUT
C2
22p
ICS84332
Figure 3. CRYSTAL INPUt INTERFACE
www.icst.com/products/hiperclocks.html
11
REV. A FEBRUARY 2, 2006