NATIONAL SEMICONDUCTOR LM1881 说明书

The LM1881 Video sync separator extracts timing informa- tion including composite and vertical sync, burst/back porch timing, and odd/even field information from standard nega- tive going sync NTSC, PAL* and SECAM video signals with amplitude from 0.5V to 2V p-p. The integrated circuit is also capable of providing sync separation for non-standard, faster horizontal rate video signals. The vertical output is produced on the rising edge of the first serration in the vertical sync period. A default vertical output is produced after a time delay if the rising edge mentioned above does not occur within the externally set delay period, such as might be the case for a non-standard video signal.

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