Pin Assignment

No. 5731-2/23

LC74788, 74788M, 74788JM

Pin Functions

Pin no.

Pin

Function

Notes

1

Ground

Ground connection (digital system ground)

2

These pins are used either to connect the crystal and capacitors used to form an external

Crystal oscillator

crystal oscillator circuit to generate the internal synchronizing signals, or to input an external

(MUTE input)

clock signal (2fsc or 4fsc). As a mask option, the XtalOUT pin can be set to function as the

3

(MUTE)

MUTE input pin. When this pin is set low, the video output is held at the pedestal level. (A pull-

up resistor is built in and the input has hysteresis characteristics.)

Switches the mode between external clock input and crystal oscillator operation. A low level

4

CTRL1

Crystal oscillator input switching

selects crystal oscillator operation and a high level selects external clock input. As a mask

(CHABLK)

(CHABLK output)

option, the CTRL1 input pin can be set to function as the CHABLK (character · frame) output.

This is a 3-value output.

5

Background line output

Outputs the range signal specified by LNA*, LNB*, and LNC*. Outputs the crystal oscillator

clock when RST is low. (This signal is not output after a reset command is executed.)

6

LC oscillator

Connections for the inductor and capacitor that form the character output dot clock generation

7

oscillator.

Outputs the state of the external synchronizing signal presence/absence judgment. Outputs a

8

External synchronizing signal

high level when synchronizing signals are present.

judgment output

Outputs the dot clock (LC oscillator) when RST is low. (This signal is not output on command

resets.)

9

CS

Enable input

Serial data input circuit enable pin. Serial data input is enabled when a low level is input.

A pull-up resistor is built in. (This input has hysteresis characteristics.)

10

SCLK

Clock input

Serial data input circuit clock input.

A pull-up resistor is built in. (This input has hysteresis characteristics.)

11

SIN

Data input

Serial data input.

A pull-up resistor is built in. (This input has hysteresis characteristics.)

12

Power supply

Composite video signal level adjustment power supply (analog system power supply)

Continued on next page.

A08688

LC74788

LC74788M

LC74788JM