Silan

Semiconductors

SC9012

HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD

Rev: 2.1

2002-02-28

3

FUNCTIONAL DESCRIPTION

1. OSCILLATION CIRCUIT

An oscillator circuit may be constructed by connecting a 480kHz or 455kHz Crystal Resonator and two capacitors

between OSCO and OSCI. Please refer to the follow diagram. Unless the keys are being operated, the oscillation is

normally stopped. Thus, power consumption is considerably reduced.

OSCO

OSCI

100pf

100pf

9

8

SC9012

455kHz

2. OSCILLATION FREQUENCY

The oscillator frequency is 455kHz, passed by a 12 division frequency circuit, can get a 37.9 ~ 39.2 frequency; 1/3

duty carrier. In addition, The oscillator frequency divided by 256, can get the basic system work time (1.78kHz). The

relation of carrier frequency (fc), internal work time period (Tm) and oscillator frequency (fosc) is given below:

fc =

1/12

× fosc

duty

1/3

Tm = 256 / fosc

Tm

the width of a high level pulse

.

Key Inputs -- KI0~KI3 of SC9012 have built-in pull-down resistors, which combined 32 keys matrix with Key Outputs

--KO0~KO7. Except the stated 6 double keys, Pressing other keys that are NOT intended for the double key

operation do NOT generate any output. Please refer to the follow diagram for the keys input matrix of SC9012.

5

1

13

9

21

17

29

25

6

2

14

10

22

18

30

26

7

3

15

11

23

19

31

27

8

4

16

12

24

20

32

28

KI0

KI1

KI2

KI3