84314AY

www.icst.com/products/hiperclocks.html

REV. C JANUARY 27, 2005

10

Integrated

Circuit

Systems, Inc.

ICS84314

The ICS84314 has been characterized with 18pF parallel resonant

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

Figure 5 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.

C1

22p

X1

18pF Parallel Cry stal

C2

22p

XTAL2

XTAL1

Figure 4A and Figure 4B show examples of termination for 2.5V

LVPECL driver. These terminations are equivalent to terminat-

ing 50

Ω to V

ground level. The R3 in Figure 4A can be eliminated and the

termination is shown in

Figure 4C.

R2

50

Zo = 50 Ohm

VCCO=2.5V

R1

50

Zo = 50 Ohm

+

-

2.5V

2,5V LVPECL

Driv er

VCCO=2.5V

R1

50

R2

50

Zo = 50 Ohm

R3

18

2,5V LVPECL

Driv er

Zo = 50 Ohm

+

-

2.5V

R2

62.5

2.5V

2,5V LVPECL

Driv er

R3

250

Zo = 50 Ohm

Zo = 50 Ohm

R4

62.5

2.5V

+

-

R1

250

VCCO=2.5V