Block Diagram

Pin Descriptions

No. 6142-5/18

LC75742E, LC75742W

Pin No.

Pin

Function

I/O

Handling when unused

3

Driver block power supply. Applications must provide a voltage in the range 8.0 to 18.0 V.

—

—

59

Logic block power supply. Applications must provide a voltage in the range 4.5 to 5.5 V.

—

—

56

Power supply ground. This pin must be connected to the system ground.

—

—

58

OSCI

I

GND

57

OSCO

O

OPEN

Reset signal input used to initialize the IC internal state. During a reset,

60

BLK

the display is turned off forcibly regardless of the internal display data.

I

GND

Also note that the internal key data is all reset to 0 and key scan operations are disabled.

However, serial data input is possible in this state.

63

CL

64

DI

I

GND

62

CE

61

DO

O

OPEN

1, 2

G1, G2

O

OPEN

44 to 4

S1 to S41

Segment outputs that display the display data transferred over the serial interface.

O

OPEN

Key scan outputs. Normally, when a key matrix is formed, diodes are inserted in the key

45 to 50

KS1 to KS6

scan timing lines to prevent shorts. However, since this IC uses unbalanced CMOS outputs

O

OPEN

in the output transistor circuit, the IC will not be damaged if these outputs are shorted.

51 to 55

KI1 to KI5

Key scan inputs. Pull-down resistors are built into the IC internal pin circuits.

I

GND

Serial data interface. These pins must be connected to the system microcontroller.

Note that since DO is an open-drain output, a pull-up resistor is required.

CL: Synchronization clock

DI: Transfer data

CE: Chip enable

DO: Output data

Oscillator circuit connections. An oscillator circuit is formed by connecting a resistor and a

capacitor externally to these pins.