844002AGI-01

www.icst.com/products/hiperclocks.html

REV. A JANUARY 5, 2006

7

Integrated

Circuit

Systems, Inc.

ICS844002I-01

The ICS844002I-01 has been characterized with 18pF paral-

lel resonant crystals. The capacitor values shown in Figure 2

below were determined using a 25MHz, 18pF parallel reso-

nant crystal and were chosen to minimize the ppm error.

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

are vulnerable to random noise. The ICS844002I-01 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 1 illustrates how

a 10

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

capacitor should be connected to each V

10

Ω

V

DDA

10

μF

.01

μF

2.5V

.01

μF

V

DD

C1

22p

X1

18pF Parallel Crystal

C2

22p

XTAL_OUT

XTAL_IN