NSC LM1201N, LM1201M Datasheet
LM1201 Video Amplifier System
General Description
The LM1201 is a wideband video amplifier system intended
for high resolution monochrome or RGB monitor applications. In addition to the wideband video amplifier the
LM1201 contains a gated differential input black level clamp
comparator for brightness control and an attenuator circuit
for contrast control. The LM1201 also contains a voltage
reference for the video input. For medium resolution RGB
color monitor applications also see the LM1203 Video Amplifier System data sheet.
Features
Y
Wideband video amplifier (200 MHz
Y
Attenuator circuit for contrast control (l40 dB range)
Y
Externally gated comparator for brightness control
@
b
3 dB)
Block and Connection Diagram
Y
Y
Y
Typical Applications
Y
Y
Y
Y
Y
Y
Y
Y
LM1201 Video Amplifier System
January 1995
Provisions for external gain set and peaking of video
amplifier
Video input voltage reference
Low impedance output driver
CRT video amplifiers
Video switches
High frequency video preamplifiers
Wideband gain controls
PC monitors
Workstations
Facsimile machines
Printers
FIGURE 1
Order Number LM1201M or LM1201N
See NS Package Number M16A or N16E
C
1996 National Semiconductor Corporation RRD-B30M56/Printed in U. S. A.
TL/H/10006
TL/H/10006– 1
Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage V
to Ground Pins, 1, 7 13.5V
Voltage at Any Input Pin (V
Pins 10, 12, 15
CC
IN
)V
CC
t
V
IN
t
GND
Video Output Current (I8)28mA
e
Package Power Dissipation at T
(Above 25
C derate based on (iJAand TJ)
§
Package Thermal Resistance (i
25§C 1.56W
A
) N16E 80§C/W
JA
Package Thermal Resistance (iJA) M16A 100§C/W
Junction Temperature (TJ) 150§C
Storage Temperature Range (T
Lead Temperature (Soldering, 10 sec.) 265§C
ESD Susceptibility 2 kV
Human body model: 100 pF discharged through a 1.5 kX
resistor
Operating Ratings (Note 4)
Temperature Range 0§Ctoa70§C
Supply Voltage (V
CC
b
)
STG
65§Ctoa150§C
) 10.8VsV
CC
s
13.2V
Electrical Characteristics See Test Circuit (Figure 2), T
DC Static Tests S9 Open; V4
e
6V; V5e0V; V6e2.0V unless otherwise stated
A
e
25§C; V
Symbol Parameter Conditions Typical Limit Limit
I
S
V
3
Supply Current VCCPins 12, 15 Only 45 57 mA(max)
Video Input Reference Voltage 2.65 2.4 V(min)
e
V
CC1
CC2
Tested Design
(Note 1) (Note 2)
e
e
V
12V
CC3
Units
(Limits)
2.95 V(max)
I
16
V
5L
V
5H
I
5L
I
5H
I
a
2
I
b
2
V
8L
V
8H
V
OS
AC Dynamic Tests S9 Closed, V
Symbol Parameter Conditions Typ
Av max Video Amplifier Gain V
DAv 5V Attenuation@5V Ref: Av max, V
DAv 2V Attenuation@2V Ref: Av max, V
THD Video Amplifier Distortion V
f(b3dB) Video Amplifier Bandwidth (Note 3) V
t
r
t
f
Note 1: These parameters are guaranteed and 100% production tested.
Note 2: Design limits are guaranteed (but not 100% production tested). These limits are not used to calculate outgoing quality levels.
Note 3: When measuring video amplifier bandwidth or pulse rise and fall times, a double sided full ground plane printed circuit board without socket is recommend-
ed.
Note 4: Operating Ratings indicate conditions of which the device is functional, but does not guarantee specific performance limits. For guaranteed specifications
and test conditions, see Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may
degrade when the device is not operated under the listed test conditions.
Video Input Bias Current (V3–V16)/10 kX 5.0 20 mA(max)
Clamp Gate Low Input Voltage Clamp Comparator On 1.2 0.8 V(min)
Clamp Gate High Input Voltage Clamp Comparator Off 1.6 2.0 V(max)
Clamp Gate Low Input Current V
Clamp Gate High Input Current V
Clamp Cap Charge Current V
Clamp Cap Discharge Current V
Video Output Low Voltage V
Video Output High Voltage V
5
5
2
2
2
2
Comparator Input Offset Voltage V6–V
e
0V, V
5
e
0V
e
12V 0.005 1 mA(max)
e
0V 1 0.55 mA(min)
e
5V
e
0V 0.5 0.9 V(max)
e
5V 8.5 8.0 V(min)
9
e
4V
6
b
0.5
b
1
g
0.5
b
5.0 mA(max)
b
0.55 mA(min)
g
25 mV(max)
Tested Design Units
Limit (Note 1) Limit (Note 2) (Limits)
e
12V 8 5.5 V/V(min)
4
Output Rise Time (Note 3) V
Output Fall Time (Note 3) V
e
5V
4
e
2V
4
e
4
e
4
e
O
e
O
5V, V
12V, V
4V
p-p
4V
p-p
e
1V
O
p-p
e
100 mV
O
b
10 dB
b
45 dB
0.3 %
200 170 MHz(min)
rms
2.5 ns
3ns
http://www.national.com 2
FIGURE 2. LM1201 AC/DC Test Circuit
TL/H/10006– 2
Note: When V
duty cycle square waves can be used for test purposes. The low frequency dominant pole is determined by C2 at Pin 2. Capacitor C9 at pin 9 prevents overloading
the clamp comparator inverting input. See applications section for additional information.
s
0.8V and S9 is closed, DC feedback around the Video Amplifier is provided by the clamp comparator. Under these conditions sine wave or 50%
5
FIGURE 3. Typical Application of the LM1201
TL/H/10006– 3
* 30X resistor is added to the input pin for protection against current surges coming from the 10 mF input capacitor. By increasing this resistor to well over 100X
the rise and fall times of the LM1201 can be increased for EMI considerations.
http://www.national.com3
APPLICATIONS INFORMATION
Figure 4
shows the block diagram of a typical analog monochrome monitor. The monitor is used with CAD/CAM work
stations, PCs, arcade games and in a wide range of other
applications that benefit from the use of high resolution display terminals. Monitor characteristics may differ in such
ways as sweep rates, screen size, or in video amplifier
speed but will still be generally configured as shown in
ure 4
. Separate horizontal and vertical sync signals may be
Fig-
required or they may be contained as a composite signal in
the video input signal. The video input signal is usually
supplied by coaxial cable which is terminated in 75X at the
monitor input and internally AC coupled to the video amplifier. The input signal is approximately 1V peak-to-peak in amplitude and at the input of the high voltage video section,
approximately 6V peak-to-peak. At the cathode of the CRT
the video signals can be as high as 60V peak to peak. The
block in
Figure 4
labeled ‘‘Video Amplification with DC Controlled Gain/Black Level’’ contains the function of the
LM1201 video amplifier system.
FIGURE 4. Typical Monochrome Monitor Block Diagram
TL/H/10006– 4
http://www.national.com 4
Circuit Description
Figure 5
is a block diagram of the LM1201 along with the
contrast and brightness controls. The contrast control is a
DC operated attenuator which varies the AC gain of the
amplifier without introducing any signal distortions or DC
output shift. The brightness control function requires a
‘‘sample and hold’’ circuit (black level clamp) which holds
the DC bias of the video amplifier and CRT cathodes constant during the black level reference portion of the video
waveform. The clamp comparator, when gated on during
this reference period, will charge or discharge the clamp
capacitor until the non-inverting input of the clamp comparator matches that of the inverting input voltage which was set
by the brightness control.
Figure 6
is a simplified schematic of the LM1201 video amplifier along with the recommended external components.
The IC pin numbers are circled with all external components
shown outside of the dashed line. The video input is applied
to pin 16 via the 10 mF coupling capacitor. DC bias to the
video input is through the 10 kX resistor which is connected
to the 2.6V reference at pin 3. The low frequency roll-off of
the amplifier is set by these two components. Transistor Q1
buffers the video signal to the base of Q2. The Q2 collector
current is then directed to the V
V
through Q4 and the 500X load resistor depending
CC2
upon the differential DC voltage at the bases of Q3 and Q4.
supply through Q3 or to
CC1
The Q3 and Q4 differential base voltage is determined by
the contrast control circuit which is described below. The
black level DC voltage at the collector of Q4 is maintained
by Q5 and Q6 which are part of the black level clamp circuit
also described below. The video signal appearing at the collector of Q4 is then buffered by Q7 and level shifted down
by Z1 and Q8 to the base of Q9 which will then provide
additional system gain.
FIGURE 5. Block Diagram of LM201 Video Amplifier with Contrast and Black Level Control
TL/H/10006– 5
http://www.national.com5
Loading...