843AG-75

www.icst.com/products/hiperclocks.html

REV. A JANUARY 9, 2006

6

Integrated

Circuit

Systems, Inc.

ICS843-75

The ICS843-75 has been characterized with 18pF parallel

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

Figure 1 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.

An unused LVCMOS output should be terminated with 100

Ω

to ground as close as possible to the device.

All unused LVPECL outputs can be left floating. We recommend

that there is no trace attached. Both sides of the differential

output pair should either be left floating or terminated.

X1

18pF Parallel Cry stal

C1

12p

XTAL_OUT

XTAL_IN

C2

12p