844246AM

www.icst.com/products/hiperclocks.html

REV. A SEPTEMBER 29, 2005

8

Integrated

Circuit

Systems, Inc.

ICS844246

PRELIMINARY

As in any high speed analog circuitry, the power supply pins

are vulnerable to random noise. The ICS844246 provides

separate power supplies to isolate any high switching

noise from the outputs to the internal PLL. V

V

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 10

Ω

resistor along with a 10

μF and a .01μF bypass capacitor

should be connected to each V

can also be replaced by a ferrite bead.

10

Ω

V

DDA

10

μF

.01

μF

3.3V

.01

μF

V

DD

The ICS844246 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.

C1

22p

X1

18pF Parallel Crystal

C2

22p

XTAL_OUT

XTAL_IN