Overview

The LC74751 is a CMOS LSI that supports on-screen display of characters and patterns on a TV screen under the control of a microcontroller. The LC74751 includes an on-chip character ROM that provides 128 characters in a 12 × 18 dot format. This IC supports display of up to 12 lines of 24 characters each for a maximum of 288 characters.

Features

• Display format: 24 characters by 12 rows

• Characters displayed: Up to 288 characters

• Display control ROM (line ROM): ROM for 64 lines

(Control in line units: lines consisting of 24 characters)

• Display RAM: 176 characters (Used for the specification

of user-defined characters.)

• Character format: 12 (horizontal) × 18 (vertical) dots

• Characters in font: 128

• Character sizes: Four sizes each in the horizontal and

vertical directions

• Initial display positions: 64 horizontal positions and 64

vertical positions

• Blinking: Specifiable in character units

• Blinking types:

— Two periods supported: 1.0 second and 0.5 second

— Three duty types supported: 25, 50, and 75

• Blanking: Over the whole font (12 × 18 dots)

• Background color

— 8 background colors (in internal synchronization

mode): 4fsc (NTSC/PAL/PAL-M/PAL-N)

— 4 background colors (in internal synchronization

mode): 2fsc (NTSC)

— Single background color (blue) (in internal

synchronization mode): 2fsc (PAL/PAL-M/PAL-N)

• External control input: Serial data input

• Synchronizing signals: Supports switching between

internal and external synchronizing signals.

• On-chip sync separator circuit

• Video output: Composite video output in the NTSC,

PAL, PAL-M, or PAL-N format

• Superimpose function: Superimposes the character

output on the composite video output.