Silan

Semiconductors

SC7461

HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD

Rev: 2.2

2002-02-28.

4

PIN DESCRIPTION

Pin No.

Symbol

I/O

Description

1~4

KI0~KI3

I

Key Input Pins

7

OUT

O

Output Pins For Transit LED Drive

--

Power Supply

9

TEST

I

LSI Test Pin. This pin is normally set to High State or Floating.

10

OSCI

I

Oscillator Input Pin

11

OSCO

O

Oscillator Output Pin

12

--

Power Supply Vss=GND

13~20

KO7~KO0

O

Key Scan Timing Signal Output Pins

21~24

5,6

C0~C3

C4~C5

I

Custom Code Input Pins. Capable of externally setting 6 out of

13 bits for custom coding.

FUNCTIONAL DESCRIPTION

1.OSCILLATION CIRCUIT

A self-biased type amplifier is housed by a CMOS Inverter Method. Thus, an oscillation circuit can be

constructed by connecting a ceramic resonator. Please refer to Figure 4 for the oscillation circuit diagram.

100pF

100pF

455KHz

SC7461

FIGURE 1. OSCILLATION CIRCUIT DIAGRAM

Unless the keys are being operated, the oscillation is normally stopped. Thus, power consumption is considerably

reduced.

2.KEY INPUT

A total of 32 keys can be connected by Key Inputs--KI0~KI3 and Timing Signals--KO0~KO7. Double Key

Operation is possible for only Key No.20 in combination with the other keys connected to the KO5 line, namely: Key

No.21, 22 or 23. Thus, only the following key combinations may be used for the double key operation:

1).Key Nos.20 and 21

2).Key Nos.20 and 22

3).Key Nos.20 and 23