Overview

The LA7945N extracts the closed caption signal overlapped in the video signal vertical retrace period and transfers the data and clock signal to a decoder IC. This IC requires the use of either an add-on type decoder, such as the LC7458B or 7457A (for I2C), or a microcontroller type decoder, such as the LC8640XX.

Features

• Adoption of a dual loop AFC allows the LA7945N to stably extract the caption signal.

• Provides the pulse outputs required by caption decoder ICs.

Functions

• Synchronization separation.

• VCO

• Vertical countdown.

• Horizontal countdown.

• Data slicing.

• Dual loop AFC.

• Field discrimination.

• Lock detection

• Vertical/horizontal pulse output.