GS1881, GS4881, GS4981 Monolithic Video Sync Separators
Features
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noise tolerant odd/even flag, back porch and
horizontal sync pulse
fast recovery from impulse noise
excellent temperature stability
0.5V to 4Vpp input signal amplitude with 5V supply
well-controlled clamp discharge current and slicing
level
programmable horizontal scan rate (up to 130kHz)
composite, vertical, back porch, odd/even (GS1881,
GS4881), horizontal (GS4981) outputs
predictable vertical output pulse width with default
trigger for non-standard video signals
Pb-free and Green
5V to 12V supply voltage range
pin compatible with LM1881 sync separator
Description
The GS1881, GS4881 and GS4981 are general purpose sync
separators for use in a wide variety of video applications.
The devices extract the timing information from composite
video signals with scan rates from 15 to 130kHz.
The GS1881 is a drop-in replacement for the industry
standard LM1881 with much improved performance. The
device generates composite sync, vertical sync, back porch
and odd/even field signals. The GS4881 is identical to the
GS1881 but features a noise immune back porch pulse
which maintains a constant H rate during the vertical
interval. The GS4981 is identical to the GS4881, except that
it provides horizontal sync in place of the odd/even output.
All three devices feature a self-adjusting windowing circuit
for noise immunity, which synchronizes to H rate. This
windowing circuit determines the odd or even field in the
GS1881 and GS4881, gates the back porch pulse in the
GS4881 and GS4981, and generates the horizontal sync
output in the GS4981.
The devices feature an improved input stage which ensures
that the input signal is sliced at a predictable point due to
well-controlled input clamp discharge current and sync
slicing level. A missing pulse detector enables the devices
to recover quickly from impulse noise disturbances by
temporarily increasing the clamp discharge current by
roughly ten times. The input stage will operate with signals
from 0.5 to 4Vp-p with a 5V supply.
The GS1881, GS4881 and GS4981 also feature a predictable
vertical output pulse width with a default trigger for
non-standard video signals. All three are available in
commercial and industrial temperature ranges and are
packaged in both DIP and SOIC.
Application Selection Chart
Application
Direct LM1881 Replacement with
Improved Performance
New Applications Substitution for
LM1881
New Applications Requiring Horizontal
Sync Output
Choose Device:
GS1881
GS4881
GS4981
GS1881, GS4881, GS4981 Monolithic Video Sync
Separators
Data Sheet
6926 - 5
November 2009
1 of 29
Proprietary & Confidential
GENNUM [ GENNUM CORPORATION ]
