National Semiconductor LM1881-X Technical data
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LM1881, LM1881-X
Video Sync Separator
LM1881, LM1881-X Video Sync Separator
June 2003
General Description
The LM1881 Video sync separator extracts timing information including composite and vertical sync, burst/back porch
timing, and odd/even field information from standard negative 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.
Connection Diagram
LM1881N
Features
n AC coupled composite input signal
>
n
10 kΩ input resistance
<
n
10 mA power supply drain current
n Composite sync and vertical outputs
n Odd/even field output
n Burst gate/back porch output
n Horizontal scan rates to 150 kHz
n Edge triggered vertical output
n Default triggered vertical output for non-standard video
signal (video games-home computers)
n -40˚C to +85˚C operation (LM1881-X)
Order Number LM1881M or LM1881N (0˚C to +70˚C)
Order Number LM1881M-X or LM1881N-X (-40˚C to +85˚C)
See NS Package Number M08A or N08E
*PAL in this datasheet refers to European broadcast TV standard “Phase Alternating Line”, and not to Programmable Array Logic.
© 2003 National Semiconductor Corporation DS009150 www.national.com
00915001
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage 13.2V
Input Voltage 3 V
LM1881, LM1881-X
Output Sink Currents; Pins, 1, 3, 5 5 mA
6V
P-P(VCC
P-P(VCC
= 5V)
≥ 8V)
Package Dissipation (Note 2) 1100 mW
Storage Temperature Range −65˚C to +150˚C
ESD Susceptibility (Note 3) 2 kV
Soldering Information
Dual-In-Line Package (10 sec.) 260˚C
Small Outline Package
Vapor Phase (60 sec.) 215˚C
Infrared (15 sec.) 220˚C
Output Sink Current; Pin 7 2 mA
Electrical Characteristics LM1881
VCC= 5V; R
Parameter Conditions Min Typ (Note 4) Max Units
Supply Current Outputs at
DC Input Voltage Pin 2 1.3 1.5 1.8 V
Input Threshold Voltage (Note 5) 55 70 85 mV
Input Discharge Current Pin 2; V
Input Clamp Charge Current Pin 2; V
R
Pin Reference Voltage Pin 6; (Note 6) 1.10 1.22 1.35 V
SET
Composite Sync. & Vertical
Outputs
Burst Gate & Odd/Even
Outputs
Composite Sync. Output I
Vertical Sync. Output I
Burst Gate Output I
Odd/Even Output I
Vertical Sync Width 190 230 300 µs
Burst Gate Width 2.7 kΩ from Pin 5 to V
Vertical Default Time (Note 7) 32 65 90 µs
= 680 kΩ;TA= 0˚C to +70˚C by correlation with 100% electrical testing at TA=25˚C
SET
V
=5V
CC
Logic 1
= 2V 6 11 16 µA
IN
= 1V 0.2 0.8 mA
IN
I
=40µA;
OUT
Logic 1
I
= 1.6 mA
OUT
Logic 1
I
=40µA;
OUT
Logic 1
= −1.6 mA; Logic 0; Pin 1 0.2 0.8 V
OUT
= −1.6 mA; Logic 0; Pin 3 0.2 0.8 V
OUT
= −1.6 mA; Logic 0; Pin 5 0.2 0.8 V
OUT
= −1.6 mA; Logic 0; Pin 7 0.2 0.8 V
OUT
= 12V
V
CC
VCC=5V
= 12V
V
CC
VCC=5V
= 12V
V
CC
VCC=5V
= 12V
V
CC
CC
4.0
11.0
2.4
10.0
4.0
11.0
2.5 4 4.7 µs
5.2
5.5
4.5
3.6
4.5
10
12
mA
V
V
V
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Electrical Characteristics LM1881–X
VCC= 5V; R
Parameter Conditions Min Typ Max Units
Supply Current Outputs at
DC Input Voltage Pin 2 1.3 1.5 1.8 V
Input Threshold Voltage 55 70 85 mV
Input Discharge Current Pin 2; V
Input Clamp Charge Current Pin 2; V
R
Pin Reference Voltage Pin 6; 1.10 1.22 1.35 V
SET
Composite Sync. & Vertical
Outputs
Burst Gate & Odd/Even
Outputs
Composite Sync. Output I
Vertical Sync. Output I
Burst Gate Output I
Odd/Even Output I
Vertical Sync Width 140 230 588 µs
Burst Gate Width 2.7 kΩ from Pin 5 to V
Vertical Default Time 32 65 90 µs
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. For guaranteed specifications and test conditions, see the
Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed.
Note 2: For operation in ambient temperatures above 25˚C, the device must be derated based on a 150˚C maximum junction temperature and a package thermal
resistance of 110˚C/W, junction to ambient.
Note 3: ESD susceptibility test uses the “human body model, 100 pF discharged through a 1.5 kΩ resistor”.
Note 4: Typicals are at T
Note 5: Relative difference between the input clamp voltage and the minimum input voltage which produces a horizontal output pulse.
Note 6: Careful attention should be made to prevent parasitic capacitance coupling from any output pin (Pins 1, 3, 5 and 7) to the R
Note 7: Delay time between the start of vertical sync (at input) and the vertical output pulse.
= 680 kΩ;TA= –40˚C to +85˚C by correlation with 100% electrical testing at TA=25˚C
SET
V
=5V
CC
Logic 1
= 2V 6 11 16 µA
IN
= 1V 0.2 0.8 mA
IN
I
=40µA;
OUT
Logic 1
I
= 1.6 mA
OUT
Logic 1
I
=40µA;
OUT
Logic 1
= −1.6 mA; Logic 0; Pin 1 0.2 0.8 V
OUT
= −1.6 mA; Logic 0; Pin 3 0.2 0.8 V
OUT
= −1.6 mA; Logic 0; Pin 5 0.2 0.8 V
OUT
= −1.6 mA; Logic 0; Pin 7 0.2 0.8 V
OUT
= 25˚C and represent the most likely parametric norm.
J
= 12V
V
CC
VCC=5V
= 12V
V
CC
VCC=5V
= 12V
V
CC
VCC=5V
= 12V
V
CC
CC
4.0
11.0
2.4
10.0
4.0
11.0
2.2 4 4.7 µs
5.2
5.5
4.5
3.6
4.5
10
12
SET
mA
V
V
V
pin (Pin 6).
LM1881, LM1881-X
Typical Performance Characteristics
R
Value Selection
SET
vs Vertical Serration
Pulse Separation
00915007 00915008
Vertical Default
Sync Delay Time
vs R
SET
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Typical Performance Characteristics (Continued)
LM1881, LM1881-X
Burst/Black Level
Gate Time vs R
SET
Vertical Pulse
Width vs Temperature
00915009
Vertical Pulse
Width vs R
SET
Supply Current vs
Supply Voltage
00915010
00915011
Application Notes
The LM1881 is designed to strip the synchronization signals
from composite video sources that are in, or similar to, the
N.T.S.C. format. Input signals with positive polarity video
(increasing signal voltage signifies increasing scene brightness) from 0.5V (p-p) to 2V (p-p) can be accommodated.
The LM1881 operates from a single supply voltage between
5V DC and 12V DC. The only required external components
besides a power supply decoupling capacitor at pin 8 and a
set current decoupling capacitor at pin 6, are the composite
input coupling capacitor at pin 2 and one resistor at pin 6 that
sets internal current levels. The resistor on pin 6 (i.e. R
allows the LM1881 to be adjusted for source signals with line
scan frequencies differing from 15.734 kHz. Four major sync
signals are available from the I/C; composite sync including
both horizontal and vertical scan timing information; a verti-
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)
set
00915002
cal sync pulse; a burst gate or back porch clamp pulse; and
an odd/even output. The odd/even output level identifies
which video field of an interlaced video source is present at
the input. The outputs from the LM1881 can be used to
gen-lock video camera/VTR signals with graphics sources,
provide identification of video fields for memory storage,
recover suppressed or contaminated sync signals, and provide timing references for the extraction of coded or uncoded
data on specific video scan lines.
To better understand the LM1881 timing information and the
type of signals that are used, refer to Figure 1(a-e) which
shows a portion of the composite video signal from the end
of one field through the beginning of the next field.
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