LMH1981 Multi-Format Video Sync Separator
PRELIMINARY
April 2006
LMH1981
Multi-Format Video Sync Separator
General Description
The LMH1981 is a high performance multi-format sync sepa-
rator ideal for use in a wide range of video applications, such
as broadcast and professional video equipment and HDTV/
DTV systems.
The input accepts standard analog video signals with either
bi-level or tri-level sync, and the outputs provide all of the
critical timing signals in CMOS logic, including composite,
horizontal, and vertical syncs, burst/back porch timing, odd/
even field, and video format outputs. The horizontal sync
output features very low jitter, minimizing external circuitry
needed to clean and reduce jitter in subsequent sync pro-
cessing stages.
The LMH1981 automatically detects the input video format,
eliminating the need for programming using a microcontroller
or external R
SET
resistor. The sync separator applies precise
50% sync slicing to ensure accurate sync extraction for
inputs with irregular amplitude, offset, and noise conditions.
Its unique video format feature (pin 9) outputs the total
vertical scan lines per frame as an 11-bit binary serial bit
stream, which can be decoded by the video system to de-
termine the input video format and enable dynamic adjust-
ment of system parameters, i.e.: color space or scaler con-
versions. The LMH1981 is available in a 14-pin TSSOP
package and operates over the full commercial temperature
range.
Features
n
Standard analog video sync separation for NTSC, PAL,
SECAM, 480i/p, 576i/p, 720p, 1080i/p, and RGsB from
composite (CVBS), S-Video (Y/C), component (YP
B
P
R
),
and computer video interfaces
n
Bi-level & tri-level sync compatible
n
Composite, horizontal, and vertical sync outputs
n
Burst/back porch timing, odd/even field, and video
format Outputs
n
Superior jitter performance on the H Sync
negative-going edge reference
n
Automatic video format detection
n
50% sync slicing of video inputs from 0.5 V
PP
to 2 V
PP
n
Macrovision compatible
n
3.3V to 5V supply operation
Applications
n
n
n
n
n
n
Broadcast and professional video equipment
HDTV/DTV systems
Genlock systems
Video capture & digitization
Set-top boxes (STB) & digital video recorders (DVR)
Video displays
Connection Diagram
14-Pin TSSOP
Pin Descriptions
Pin No.
1
2, 5, 10
3, 6, 11
4
7
8
9
12
13
14
20174501
Pin Name
R
EXT
GND
V
CC
V
IN
HSOUT
VSOUT
VFOUT
CSOUT
BPOUT
OEOUT
Pin Description
Bias Current External Resistor
Ground
Supply Voltage
Video Input
Horizontal Sync Output
Vertical Sync Output
Video Format Output
Composite Sync Output
Burst/Back Porch Timing Output
Odd/Even Field Output
Top View
FIGURE 1. Pinout
Ordering Information
Package
14-Pin TSSOP
Part Number
LMH1981MT
LMH1981MTX
DS201745
Package Marking
LMH1981MT
Transport Media
94 Units/Rail
2.5k Units Tape and Reel
NSC Drawing
MTC14
漏 2006 National Semiconductor Corporation
www.national.com
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