LM1270
Hi-Brite 200 MHz I
2
C Compatible RGB Image Enhancer
with Video Auto Sizing
General Description
The LM1270 is a supplementary IC to the low cost chipset
(LCCS). It modifies the video stream prior to the LCCS
preamplifier. The key function of the LM1270 is image pro-
cessing for enhancing pictures or motion video. Image en-
hancement is accomplished by special intermediate fre-
quency boosting. 200 MHz bandwidth assures minimal
impact on the video change when adding the LM1270.
Other functions of the LM1270 are:
1.
Measures the length of the active video and its front
porch time with respect to the horizontal flyback and
vertical sync for auto alignment information.
2.
Calibration mode for determining the start of the image
coordinates.
3.
Data receiver for receiving data encoded on video.
4.
Window highlight with respect to the horizontal and ver-
tical sync, used with the image enhancing feature.
5.
Video source selection, allowing the choice of two ana-
log inputs.
Features
n
Ideal companion IC to the LCCS to provide image
enhancing for viewing pictures or motion video
n
Programmable clamp generator
n
Programmable blank generator
n
Video detection controlled by I
2
C compatible bus,
allowing easy and accurate Hi-Brite window calibration
n
Programmable window Hi-Brite function
n
Programmable image sharpness control (TV emphasis),
adjustable for different line rates
n
Measures video position with respect to the horizontal
flyback and vertical sync pulses, providing necessary
information for auto-sizing
n
Emphasis done either inside or outside the window
Applications
n
Any monitor designed with the LCCS chip set
n
Standard 0.7V video output assures compatibility with
any video pre-amp
Block and Connection Diagram
20063501
FIGURE 1. Order Number LM1270N
See NS Package Number N24D
May 2003
LM1270
Hi-Brite
200
MHz
I
2
C
Compatible
RGB
Image
Enhancer
with
V
ideo
Auto
Sizing
2003 National Semiconductor Corporation
DS200635
www.national.com
Absolute Maximum Ratings
(Notes 1,
3)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage, Pins 9 and 18
6.0V
Peak Video Output Source Current
(Any One Amp) Pins 19, 20 or 21
28 mA
Voltage at Any Input Pin
(V
IN
)
V
CC
+0.5
>
V
IN
>
-0.5V
Power Dissipation (P
D
)
(Above 25C Derate Based
on
JA
and T
J
)
2.4W
Thermal Resistance to Ambient (
JA
)
51C/W
Thermal Resistance to Case (
JC
)
32C/W
Junction Temperature (T
J
)
150C
ESD Susceptibility (Note 4)
2 kV
ESD Machine Model (Note 5)
200V
Storage Temperature
-65C to +150C
Lead Temperature (Soldering, 10 sec.)
265C
Operating Ratings
(Note 2)
Temperature Range
0C to +70C
Supply Voltage (V
CC
& PLL V
CC
)
4.75V
<
V
CC
<
5.25V
Video Inputs
0.0V
<
V
IN
<
1.0V
P-P
Active Video Signal Electrical Characteristics
Unless otherwise noted: T
A
= 25C, V
CC
= +5V, V
IN
= 0.7V, C
L
= 5 pF, Video Signal Output = 0.7V
P-P
.
Symbol
Parameter
Conditions
Min
(Note 7)
Typ
(Note 6)
Max
(Note 7)
Units
I
CC
Maximum Supply Current
Both Supplies, R
L
=
(Note 8)
165
235
mA
I
CC-PS
Maximum Supply Current, Power
Save Mode
Both Supplies, R
L
=
(Note 8)
15
25
35
mA
LE
Linearity Error
Triangular Signal Input Source
(Note 9)
5
%
V
O BLK TYP
Typical Video Black Level Output
Test Setting 4, No AC Input Signal
1.2
1.4
1.6
VDC
V
O BLK A-B
Typical Video Black Level
Difference A-B
No AC Input Signal
-0.05
0
0.05
VDC
V
O WHITE-MAX
White Level Video Output Voltage
Video in = 0.7V
0.9
1.0
1.1
V
t
r
Rise Time
10% to 90%, AC Input Signal
(Note 10)
1.9
ns
OS
R
Overshoot (Rising Edge)
AC Input Signal (Note 10)
6
%
t
f
Fall Time
90% to 10%, AC Input Signal
(Note 10)
2.0
ns
OS
F
Overshoot (Falling Edge)
AC Input Signal (Note 10)
8
%
f (-3 dB)
Video Amplifier Bandwidth
(Note 12)
V
O
= 1V
P-P
200
MHz
V
SEP
10 kHz
Video Amplifier 10 kHz Isolation
(Note 14)
-70
dB
V
SEP
10 MHz
Video Amplifier 10 MHz Isolation
(Note 14)
-50
dB
A
V MAX
Maximum Voltage Gain
Reg. 09 & 0A = 7Fh, AC Input
Signal
1.3
1.4
1.5
V/V
A
V 1/2
Contrast
@
50% Level
Reg. 09 & 0A = 40h, AC Input
Signal
-5
dB
A
V MIN
Maximum Contrast Attenuation
Reg. 09 & 0A = 00h, AC Input
Signal
-10
dB
A
V MATCH
Absolute Gain Match
@
A
V MAX
Reg. 09 & 0A = 7Fh, AC Input
Signal
0.5
dB
A
V TRACK
Gain Change between Amplifiers
Tracking When Changing A
V MAX
to
A
V 1/2
(Note 11)
0.5
dB
VID
THRESHOLD
Video Threshold
Normal Operation
80
mV
V
CLAMP MAX
Clamp Gate Low Input Voltage
Default Mode, Clamp Comparators
Off
2.2
V
V
CLAMP MIN
Clamp Gate High Input Voltage
Default Mode, Clamp Comparators
On
2.8
V
I
CLAMP LOW
Clamp Gate Input Current
Default Mode, V
24
= 0V
-1.6
-1.4
-1.1
mA
LM1270
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2
Active Video Signal Electrical Characteristics
(Continued)
Unless otherwise noted: T
A
= 25C, V
CC
= +5V, V
IN
= 0.7V, C
L
= 5 pF, Video Signal Output = 0.7V
P-P
.
Symbol
Parameter
Conditions
Min
(Note 7)
Typ
(Note 6)
Max
(Note 7)
Units
I
CLAMP HIGH
Clamp Gate Input Current
Default Mode, V
24
= 4V
0.5
0.7
0.9
mA
t
PW CLAMP
Back Porch Clamp Pulse Width
Default Mode (Note 15)
200
ns
t
CLAMP-VIDEO
End of Clamp Pulse to Start of
Active Video
Default Mode, Limit Is Guaranteed
by Design
50
ns
V
CLAMP HIGH OUT
Clamp Gate High Output Voltage
Internal Clamp Is Output at Pin 24
3.2
V
I
CLAMP HIGH OUT
Clamp Gate High Output Current
Internal Clamp Is Output at Pin 24
10
A
V
CLAMP LOW OUT
Clamp Gate Low Output Voltage
Internal Clamp Is Output at Pin 24
0.4
V
I
CLAMP LOW OUT
Clamp Gate Low Output Current
Internal Clamp Is Output at Pin 24
-10
A
R
IN-VIDEO
Input Resistance
20
M
V
REF
R
EXT
V
REF
R
EXT
Output Voltage
10 k
, 1% Resistor; Pin 23 to GND
1.26
1.44
1.64
V
V
SPOT
Spot Killer Voltage
V
CC
Adjusted to Activate
3.40
4.0
4.25
V
External Interface Signals Electrical Characteristics
Unless otherwise noted: T
A
= 25C, V
CC
= +5V, V
IN
= 0.7V, C
L
= 5 pF, Video Output = 0.7 V
P-P
.
Symbol
Parameter
Conditions
Min
(Note 7)
Typ
(Note 6)
Max
(Note 7)
Units
V
L
(I
2
C)
I
2
C compatible Low Input Voltage
SDA or SCL Inputs
-0.5
1.5
V
V
H
(I
2
C)
I
2
C compatible High Input Voltage
SDA or SCL Inputs
3.0
V
CC
+
0.5
V
I
L
(I
2
C)
I
2
C compatible Low Input Current
SDA or SCL, Input Voltage = 0.4V
10
A
I
H
(I
2
C)
I
2
C compatible High Input Current
SDA or SCL, Input Voltage = 4.5V
10
A
V
OL
(I
2
C)
I
2
C compatible Low Output Voltage
I
O
= 3 mA
0.5
V
I
IN THRESHOLD
I
IN
H-Flyback Detection Threshold
-35
A
I
IN-OPERATING
Minimum -- Insure Normal
Operation
Lowest Operating Horizontal
Frequency in Given Application
(Note 15)
-50
A
Maximum -- Should Not Exceed in
Normal Operation
-550
I
IN FLYBACK
Peak Current during Flyback
Period, Recommended Design
Range
Operating Range for All Horizontal
Scan Frequencies, Maximum
Current Should Not Exceed 4 mA
(Note 15)
2.0
3.0
4.0
mA
Note 1: Limits of Absolute Maximum Ratings indicate limits below which damage to the device must not occur.
Note 2: Limits of operating ratings indicate required boundaries of conditions for which the device is functional, but may not meet specific performance limits.
Note 3: All voltages are measured with respect to GND, unless otherwise specified.
Note 4: Human body model, 100 pF capacitor discharged through a 1.5 k
resistor.
Note 5: Machine Model ESD test is covered by specification EIAJ IC-121-1981. A 200 pF capacitor is charged to the specified voltage, then discharged directly into
the IC with no external series resistor (resistance of discharge path must be under 50
).
Note 6: Typical specifications are specified at +25C and represent the most likely parametric norm.
Note 7: Tested limits are guaranteed to National's AOQL (Average Outgoing Quality Level).
Note 8: The supply current specified is the quiescent current for V
CC
with R
L
=
. Load resistors are not required and are not used in the test circuit, therefore all
the supply current is used by the pre-amp.
Note 9: Linearity Error is the variation in step height of a 16 step staircase input signal waveform with a 0.7 V
P-P
level at the input, subdivided into 16 equal steps,
with each step approximately 100 ns in width.
Note 10: Input from signal generator: t
r
, t
f
<
1 ns. Scope and generator response used for testing: t
r
= 1.1 ns, t
f
= 0.9 ns. Using the RSS technique the scope and
generator response have been removed from the output rise and fall times.
Note 11:
A
V
track is a measure of the ability of any two amplifiers to track each other and quantifies the matching of the three gain stages. It is the difference in
gain change between any two amplifiers with the contrast set to A
V 1/2
and measured relative to the A
V
max condition. For example, at A
V
max the three amplifiers'
gains might be 0.1 dB, -0.1 dB, and -0.2 dB and change to -5.2 dB, -4.9 dB and -4.7 dB respectively for contrast set to A
V 1/2
. This yields a typical gain change
of -5.0 dB with a tracking change of
0.2 dB.
Note 12: Adjust input frequency from 10 MHz (A
V
max reference level) to the -3 dB corner frequency (f
-3 dB
).
Note 13: Measure output levels of the other two undriven amplifiers relative to the driven amplifier to determine channel separation. Terminate the undriven amplifier
inputs to simulate generator loading. Repeat test at f
IN
= 10 MHz for V
SEP 10 MHz
.
Note 14: A minimum pulse width of 200 ns is guaranteed for a horizontal line of 15 kHz. This limit is guaranteed by design. If a lower line rate is used then a longer
clamp pulse may be required.
LM1270
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3
External Interface Signals Electrical Characteristics
(Continued)
Note 15: Limits met by matching the external resistor going to pin 24 to the H Flyback voltage.
Typical Performance Characteristics
V
CC
= 5V, T
A
= 25C unless otherwise specified.
Emphasis, Center Frequency at Maximum
Center Frequency, Emphasis at Maximum
20063502
20063503
The above two plots show the processing done by the
LM1270 on the video input signal. There are two variables
for the video processing, emphasis and center frequency.
Emphasis is controlled by bits 0-2 in register 0B. This gives
8 different levels of emphasis. In the above plot the center
frequency is set at its maximum level and the 8 different
levels of emphasis is measured. The output video with no
emphasis is adjusted to a 0.7 V
P-P
level. Using maximum
emphasis the video is increased to a 0.9 V
P-P
level at the
rising edge of the video. If the falling edge was measured it
would show a similar waveform, but going in the negative
direction.
Center frequency is shown in the second plot. Control of the
center frequency is done with bits 0-3 in register 0C. This
gives 16 adjustments for this feature. Every other adjustment
is shown in the above plot, showing all 16 adjustments would
have made the plot too hard to read. The curves closely
approximate the peaking of an RC network, therefore the
term center frequency means the RC time constant that is
approximated by each curve in the above plot. A true RC
peaking network would give very large overshoots. The
LM1270 has special circuitry to clip the very large over-
shoots, yet has the complete benefit of the RC peaking. This
special circuitry allows for much more overshoot than one
could do with RC peaking and still not saturate the video
channel.
Note that the video channel with the emphasis also has its
own independent contrast control. This allows the user to
adjust his monitor for a brighter picture within the Hi-Brite
window and optimize the emphasis for the resolution he is
using with the monitor. Now the user of the monitor can give
his pictures or video a special "sparkle" when using the
capabilities of the LM1270.
LM1270
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4
Pin Descriptions
Pin
No.
Pin Name
Schematic
Description
1
2
3
Blue 1 Video In
Red 1 Video In
Green 1 Video In
Channel 1 video inputs. These inputs must be AC
coupled with a 0.1 F cap. DC restoration is done at
these inputs. A series resistor of about 33
and
external ESD protection diodes should also be used.
Channel 1 video passes through the emphasis
section used for the Hi-Brite window. When using
Hi-Brite the channel 1 input pin must be shorted to
the corresponding channel 2 input pin.
4
Analog Input
Ground
Ground Pin for the input analog circuits of the
LM1270
5
6
7
Blue 2 Video In
Red 2 Video In
Green 2 Video In
Channel 2 video inputs. These video inputs must be
AC coupled with a 0.1 F cap. DC restoration is
done at these inputs. A series resistor of about 33
and external ESD protection diodes should also be
used. When using Hi-Brite the channel 2 input pin
must be shorted to the corresponding channel 1
input pin.
8
10
Digital Ground
PLL V
CC
The ground pin should be connected to the rest of
the circuit ground by a short but independent PCB
trace to prevent contamination by extraneous
signals. The V
CC
pin should be isolated from the
rest of the V
CC
line by a ferrite bead and bypassed
to pin 8 with an electrolytic capacitor and a high
frequency ceramic.
9
PLL Filter
Recommended topology and values are shown to
the left. It is recommended that both filter branches
be bypassed to the independent ground as close to
pin 8 as possible. Great care should be taken to
prevent external signals from coupling into this filter
from video, I
2
C compatible bus, etc.
11
V Sync
Logic level vertical sync signal received from the
video card in the PC or sync stripper circuit.
LM1270
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