8402AY

www.icst.com/products/hiperclocks.html

REV. B OCTOBER 6, 2004

10

Integrated

Circuit

Systems, Inc.

ICS8402

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

are vulnerable to random noise. The ICS8402 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 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

10

Ω

V

DDA

10

µF

.01

µF

3.3V

.01

µF

V

DD

ICS84332

XTAL_IN

XTAL_OUT

X1

18pF Parallel Cry stal

C2

22p

C1

22p

ICS8402

The ICS8402 has been characterized with 18pF parallel resonant

crystals. The capacitor values, C1 and C2, shown in

Figure 3 below

were determined using a 25MHz, 18pF parallel resonant crystal and

were chosen to minimize the ppm error. The optimum C1 and C2

values can be slightly adjusted for different board layouts.