84324EM

www.icst.com/products/hiperclocks.html

REV. A SEPTEMBER 18, 2003

8

Integrated

Circuit

Systems, Inc.

ICS84324

PRELIMINARY

A crystal can be characterized for either series or parallel mode

operation. The ICS84324 has a built-in crystal oscillator circuit.

This interface can accept either a series or parallel crystal without

additional components and generate frequencies with accuracy

suitable for most applications. Additional accuracy can be

achieved by adding two small capacitors C1 and C2 as shown in

Figure 4.

C2

22pF

C1

18pF

25MHz

X1

ICS84324

19

20

XTAL2

XTAL1

Figure 5A shows a schematic example of using an ICS84324. 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[1:0]=11 therefore the output frequency is 125MHz. It is

recommended to have one decouple capacitor per power pin.

Each decoupling capacitor should be located as close as pos-

sible 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

CCA

pin as possible.

RU2

1K

F_SEL1

C16

10u

F_SEL1

R2

50

(U1,13)

Zo = 50

C2

18p

C1

22p

Zo = 50

C11

0.1u

VCC=3.3V

R7

24

e.g. F_SEL[1:0]=11

VCCA

RD2

SP

C3

0.1u

VCC

R5

1K

C6

0.1u

F_SEL0

X1

25MHz,18pF

R4

1K

F_SEL0

VCC

C5

0.1u

RU3

1K

R3

50

SP = Spare, Not Installed

VCC

U2

ICS84324

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

VEE

XTAL2

XTAL1

MR

F_SEL1

F_SEL0

VCCO

(U1,16)

(U1,24)

+

-

R1

50

VCC

VCC

RD3

SP