843256AM

www.icst.com/products/hiperclocks.html

REV. A NOVEMBER 29, 2005

8

Integrated

Circuit

Systems, Inc.

ICS843256

PRELIMINARY

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

are vulnerable to random noise.The ICS843256 provides sepa-

rate power supplies to isolate any high switching

noise from the outputs to the internal PLL. V

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 iso-

lation is required. Figure 1 illustrates how a 10

Ω resistor along

with a 10

μF and a .01μF bypass capacitor should be con-

nected to each V

placed by a ferrite bead.

10

Ω

V

CCA

10

μF

.01

μF

3.3V

.01

μF

V

CC

The ICS843256 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

18p

X1

18pF Parallel Crystal

C2

22p

XTAL_IN

XTAL_OUT