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.
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