LM1201N National Semiconductor, LM1201N Datasheet - Page 7

• Manufacturer Part Number: LM1201N
• Description: IC VIDEO AMP SYSTEM 16DIP
• Manufacturer: National Semiconductor

Specifications of LM1201N

• Applications: General Purpose
• Number Of Circuits: 1
• -3db Bandwidth: 170MHz
• Current - Supply: 45mA
• Current - Output / Channel: 28mA
• Voltage - Supply, Single/dual (±): 10.8 V ~ 13.2 V
• Mounting Type: Through Hole
• Package / Case: 16-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: *LM1201N; LM1201

Circuit Description
The ‘‘Drive’’ pin will allow the user to set the maximum gain
of the amplifier based on the range of input video signal
levels and the CRT stage gain if it is fixed or limited When
using three LM1201 devices for high resolution RGB appli-
cations the ‘‘Drive’’ pin allows the user to trim the gain of
each channel to correct for differences in the three CRT
cathodes A small capacitor (12 pF) in shunt with a 51
drive resistor at this pin will extend the high frequency gain
of the video amplifier by compensating for some of the inter-
nal high frequency roll off The 51
tem gain to approximately 8 or 18 dB The video signal at
the collector of Q9 is buffered and level shifted down by
Q10 and Q11 to the base of the output emitter follower Q12
Between the emitter of Q12 and the video output pin is a
50
tions when driving capacitive loads An external emitter re-
sistor must be added between the video output pin and
ground The value of this resistor should not be less than
330
ed when worst case (high supply max supply current max
temp) calculations are made If negative going pulse slewing
is a problem because of high capacitive loads (
more efficient method of emitter pull down would be to con-
nect a suitable resistor to a negative supply voltage This
has the effect of a current source pull down when the minus
supply voltage is
mately 10 mA The system gain will also increase slightly
because less signal will be lost across the internal 50
sistor Precautions must be taken to prevent the video
resistor which is included to prevent spurious oscilla-
otherwise package power limitations may be exceed-
b
12V and the emitter current is approxi-
FIGURE 7 LM1201 Video Input Voltage Reference and Contrast Control Circuits
(Continued)
resistor will set the sys-
l
10 pF) a
re-
7
Figure 7 shows the internal construction of the pin 3 2 6V
output pin from going below ground since IC substrate cur-
rents may cause erratic operation The collector current
from the video output transistor is returned to the power
supply at V
culations note that the datasheet specifies only the V
and V
contribution of V
emitter pull down load
In normal operation the minimum black level voltage that
can be set at the video output pin is approximately 2V at
maximum contrast setting In applications that require a low-
er black level voltage a resistor (approximately 16 k ) can
be added from pin 3 to ground This has the effect of raising
the DC voltage at the collector of Q4 which will extend the
range of the black level clamp by allowing Q5 to remain
active In applications that require video amplifier shutdown
due to fault conditions detected by monitor protection cir-
cuits pin 3 and the wiper arms of the contrast and bright-
ness controls can be grounded without harming the IC This
assumes some series resistance between the top of the
control potentiometers and V
reference circuit which is used to provide temperature and
supply voltage tracking compensation for the video amplifier
input The value of the external DC biasing resistors should
not be larger than 10 k
LM1201 (e g in RGB systems) because minor differences in
input bias currents on the individual video amplifiers may
cause offsets in gain
CC2
supply currents at 12V The IC power dissipation
CC3
pin 10 When making power dissipation cal-
CC3
is dependent upon the video output
CC
when using more than one
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CC1