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.