844003AGI

www.icst.com/products/hiperclocks.html

REV. B AUGUST 25, 2005

9

Integrated

Circuit

Systems, Inc.

ICS844003I

PRELIMINARY

The ICS844003I has been characterized with 18pF parallel

resonant crystals. The capacitor values shown in Figure 3 below

were determined using a 31.25MHz or 26.041666MHz 18pF paral-

lel resonant crystal and were chosen to minimize the ppm error.

ICS844003I

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

are vulnerable to random noise. The ICS844003I provides

separate 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 isolation is required. Figure 2 illustrates how

a 10

Ω resistor along with a 10μF and a .01μF bypass

capacitor should be connected to each V

resistor can also be replaced by a ferrite bead.

10

Ω

V

DDA

10

μF

.01

μF

3.3V

.01

μF

V

DD

C1

22p

X1

18pF Parallel Crystal

C2

22p

XTAL_OUT

XTAL_IN