ICS843004-02 Datasheet, PDF (7/12 Pages) Integrated Circuit Systems – CRYSTAL-TO-3.3V LVPECL FREQUENCY SYNTHESIZER

Integrated
Circuit
Systems, Inc.
PRELIMINARY
ICS843004-02
CRYSTAL-TO-3.3V 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 ICS843004-02 provides
separate power supplies to isolate any high switching
noise from the outputs to the internal PLL. V_CC, V_CCA, and V_CCO
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 1 illustrates how
a 10Ω resistor along with a 10µF and a .01µF bypass
capacitor should be connected to each V_CCA.
3.3V
V_CC
.01µF 10Ω
V
CCA
.01µF
10µF
FIGURE 1. POWER SUPPLY FILTERING
RECOMMENDATIONS FOR UNUSED INPUT AND OUTPUT PINS
INPUTS:
OUTPUTS:
CRYSTAL INPUT:
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 1kΩ resistor can be
tied from XTAL_IN to ground.
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.
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
1kΩ resistor can be tied from the TEST_CLK to ground.
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.
843004AG-02
www.icst.com/products/hiperclocks.html
7
REV. A JULY 20, 2005