84326AM

www.icst.com/products/hiperclocks.html

REV. A MARCH 10, 2003

9

Integrated

Circuit

Systems, Inc.

ICS84326

PRELIMINARY

The ICS84326 has been characterized with 18pF parallel

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

in

Figure 4 below were determined using a 25MHz, 18pF

C2

22pF

C1

18pF

25MHz X1

ICS84326

19

20

XTAL2

XTAL1

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.

Figure 5A shows a schematic example of using an ICS84326. In

this example, the input is a 25MHz parallel resonant crystal with

load capacitor CL=18pF. The frequency fine tuning capacitors C1

and C2 is 22pF and 18pF respectively. This example also shows

logic control input handling. The configuration is set at F_SEL=0,

therefore, the output frequency is 150MHz. It is recommended to

have one decouple capacitor per power pin. Each decoupling ca-

pacitor should be located as close as possible to the power pin.

The low pass filter R7, C11 and C16 for clean analog supply should

also be located as close to the V

X1

25MHz,18pF

C5

0.1u

R6

1K

VCCA

R2

50

VCC

+

-

R5

1K

VCC

R3

50

VCC=3.3V

U1

ICS84326

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

Q0

nQ0

Q1

nQ1

Q2

nQ2

Q3

nQ3

Q4

nQ4

Q5

nQ5

VCCO

VEE

PLL_SEL

VCC

VCCA

nc

XTAL2

XTAL1

MR

nc

F_SEL

VCCO

(U1,24)

C6

0.1u

C16

10u

VCC

(U1,13)

C2

18p

VCC

R7

24

R1

50

C11

0.1u

Zo = 50

Zo = 50

R4

1K

(U 1,16)

C3

0.1u

C1

22p