Silan

Semiconductors

SC9256

HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD

REV: 1.0

2002.01.30.

9

As fig.2 shows, the clock necessary for internal operation is produced by connecting a crystal oscillator between

capacitors. Use the crystal oscillator selection bit to select an oscillating frequency of 3.6MHz, 4.5MHz, 7.2MHz or

10.8MHz which matches that of the crystal oscillator used.

LSB

MSB

Address D0H

OSC1 OSC2

OSC1

OSC2

OSCILLATOR

FREQUENCY

00

0

1

01

11

3.6MHz

4.5MHz

7.2MHz

10.8MHz

Divider

XT

XT

C

C

X'tal

C=30pF Typ.

Fig.2

Note: set to 3.6MHz (OSC1=”0” and OSC2=”0”) when power is turned on. The crystal is not oscillating at this time

because the system is in standby mode.

Reference counter (Reference frequency divider)

The reference counter section consists of a crystal oscillator and a counter.

A crystal oscillator frequency of 3.6MHZ, 7.2MHZ or 10.8MHZ can be selected .A maximum of 15 reference

frequencies can be generated.

1. Setting reference frequency

The reference frequency is set using bits R0~R3.

LSB

MSB

Address D0H

R3

R2

R0

R1

R2

R3

000

0

00

0

1

010

0

110

0

001

0

101

0

011

0

111

0

REFERENCE

FREQUENCY

R0

R1

R2

R3

0

001

1

001

0

101

1

101

0

011

1

011

0

111

1

111

0.5 KHz

1KHz

2.5 KHz

3KHz

3.125 KHz

*3.90654 KHz

5KHz

6.25 KHz

*7.8125 KHz

REFERENCE

FREQUENCY

9KHz

10 KHz

12.5 KHz

25 KHz

50 KHz

100 KHz

Standby mode (*1)

R1

R0