DATASHEET
EL4581 FN7172
Rev 2.00
November 12, 2010 Sync Separator, 50% Slice, S-H, Filter
The EL4581 extracts timing information from standard
negative going video sync found in NTSC, PAL and SECAM
broadcast systems. It can also be used in non standard
formats and with computer graphics systems at higher scan
rates, by adjusting a single external resistor. When the input
does not have correct serration pulses in the vertical interval,
a default vertical output is produced. Features Outputs are composite sync, vertical sync, burst/back porch
output, and odd/even output. The later operates only in
interlaced scan formats. Decodes non-standard verticals The EL4581 provides a reliable method of determining
correct sync slide level by setting it to the mid-point between
sync tip and blanking level at the back porch. This 50% level
is determined by two internal self timing sample and hold
circuits that track sync tip and back porch levels. This also
provides a degree of hum and noise rejection to the input
signal, and compensates for varying input levels of 0.5VP-P
to 2.0VP-P.
A built in linear phase, third order, low pass filter attenuates
the chroma signal in color systems to prevent incorrectly set
color burst from disturbing the 50% sync slide. …
