NSC LM1208N Datasheet

OBSOLETE

LM1208
130 MHz/85 MHz RGB Video Amplifier System with
Blanking

General Description

The LM1208 is a very high frequency video amplifier system
intended forusein high resolution RGB monitor applications.
In addition to the three matched video amplifiers, the
LM1208 contains three gated single ended input black level
clamp comparators for brightness control, three matched DC
controlled attenuators for contrast control, and three DC
controlled sub-contrast attenuators providing independent
full range gain control in each channel for wide range white
balance. All DC control inputs offer high input impedance
and an operation range from 0V to 4V for easy interface to
bus controlled alignment systems. The LM1208 also con­tains a blanking circuit which clamps the video output volt­age during blanking to within 0.1V above ground. This fea­ture provides blanking capability at the cathodes of the CRT.
A spot killer is provided for CRT phosphor protection during
power-down.

Features

n Three wideband video amplifiers 130 MHz (LM1208)

−3 dB (4 VPPoutput)

n Matched (

control

±

0.1 dB or 1.2%) attenuators for contrast

n ESD susceptibility above 3 kV
n Three externally gated single ended input comparators

for cutoff and brightness control

n 0V to 4V, high input impedance DC contrast control

>

40 dB range)

(

n 0V to 4V, high input impedance DC full range gain

control (Drive) for each video channel (

n Spot killer, blanks output when V
n Capable of 7 V

bandwidth)

n Output stage blanking
n Output stage directly drives most hybrid or discrete CRT

drivers

output swing (slight reduction in

PP

>

<

10.6V

CC

Applications

n High resolution RGB CRT monitors
n Video AGC amplifiers
n Wideband amplifiers with gain and DC offset controls
n Interface amplifiers for LCD or CCD systems

@

LM1208 130 MHz/85 MHz RGB Video Amplifier System with Blanking

October 2001

40 dB range)

Block and Connection Diagram

Order Number LM1208 See NS Package Number N28B

DS100083-1

FIGURE 1.

© 2001 National Semiconductor Corporation DS100083 www.national.com

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

LM1208

please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Supply Voltage (V

Pins 3, 11, 22, 23, 25 (Note 3) 15V

Peak Video Output Source Current

(Any One Amp) Pins 17, 20 or 26 28 mA
Voltage at Any Input Pin (V
Power Dissipation (P

(Above 25˚C Derate Based on θ

and TJ) 2.5W

)

CC

)V

IN

)

D

JA

CC

≥ VIN≥ GND

Thermal Resistance (θ
Junction Temperature (T
ESD Susceptibility (Note 4) 3 kV
ESD Machine Model (Note 15) 350V
Storage Temperature −65˚C to 150˚C
Lead Temperature

(Soldering, 10 sec.) 265˚C

Operating Ratings(Note 2)

Temperature Range −20˚C to 80˚C
Supply Voltage (V

) 50˚C/W

JA

) 150˚C

J

) 10.8V ≤ VCC≤ 13.2V

CC

DC Electrical Characteristics

See DC Test Circuit
less otherwise stated.

Symbol Parameter Conditions Typical Limit Units

I

S

V

4, 6, 9

R

IN

V

14l

V

14h

I

14l

I

14h

I

clamp

I

bias

V

13l

V

13h

I

13l

I

13h

V

OL

V

OH

V

O(1V)

∆V

O(1V)

V

(blanked) Video Output Blanked Voltage V13= 0V 35 70 mV (max)

OL

I

12, 15, 18 or 28

I

16, 19 and 27

V

spot

(Figure 2),

TA= 25˚C; V

CC1=VCC2

= 12V. V12= 4V; V14= 0V; V

= 1.0V; V13= 4V; V

cut-off

(Note 5) (Note 6)

Supply Current V

CC1+VCC2,RL

=∞(Note 7) 90 105 mA (max)
Video Amplifier Input Bias Voltage 2.8 V
Video Input Resistance Any One Amplifier 20 kΩ
Clamp Gate Low Input Voltage Clamp Comparators On 1.2 0.8 V (max)
Clamp Gate High Input Voltage Clamp Comparators Off 1.6 2.0 V (min)
Clamp Gate Low Input Current V14= 0V −1 −5 µA (max)
Clamp Gate High Input Current V14= 12V 0.01 1.0 µA (max)
Clamp Cap Charge Current Clamp Comparators On

±

750

±

500 µA (min)
Clamp Cap Bias Discharge Current Clamp Comparators Off 500 nA
Blank Gate Low Input Voltage Blank Gate On 1.2 0.8 V (max)
Blank Gate High Input Voltage Blank Gate Off 1.6 2.0 V (min)
Blank Gate Low Input Current V13= 0V −5.0 −11.0 µA (max)
Blank Gate High Input Current V13= 12V 0.01 1.0 µA (max)
Video Output Low Voltage V
Video Output High Voltage V
Video Black Level Output Voltage V

Video ∆ Black Level Output Voltage Between Any Two Amplifiers,

Contrast/Drive Control Input Current V
Cut-Off Control Input Current (All Inputs) V

= 0V 0.15 0.5 V (max)

cut-off

= 9V 7.5 7 V (min)

cut-off

= 1V 1.0 V

cut-off

±

100 mV (max)

V

=1V

cut-off

=V

contrast

= 0V to 4V −500 nA

cut-off

= 0V to 4V −250 nA

drive

Spot Killer Voltage VCCAdjusted to Activate 10.4 10.8 V (max)

drive

= 4V un-

(Note 8)

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AC Electrical Characteristics (Note 14)

LM1208

See AC Test Circuit (

Figure 3

),TA= 25˚C; V

CC1=VCC2

= 12V. Manually adjust Video Output pins 17, 20, and 26 to 4V DC

for the AC test unless otherwise stated.

Symbol Parameter Conditions Typical Limit Units

(Note 5) (Note 6)

A

V max

∆A

V2V

∆A

V 0.25V

∆Drive

2V

∆Drive

0.25V

A

V match

A

V track1

THD Video Amplifier Distortion V
f (−3 dB) Video Amplifier Bandwidth V12 = 4V, V

tr(Video) Video Output Rise Time (Note 11) VO=4V

t

(Video) Video Output Fall Time (Note 11) VO=4V

f

V

10 kHz Video Amplifier 10 kHz Isolation V12 = 4V (Note 13) −70 dB

sep

V

10 MHz Video Amplifier 10 MHz Isolation V12 = 4V (Note 11) (Note 13) −50 dB

sep

t

(Blank) Blank Output Rise Time (Note 11) Blank Output = 1 V

r

t

(Blank) Blank Output Fall Time (Note 11) Blank Output = 1 V

f

t

(Clamp) Min. Back Porch Clamp Pulse

pw

Video Amplifier Gain V12 = 4V, VIN= 635 mV

V

= 4V 16.9 15.6 dB (min)

drive

PP

7.0 6.0 V/V (min)

Attenuation@2V Ref: AVmax, V12 = 2V −6 dB
Attenuation@0.25V Ref: AVmax, V12 = 0.25V −40 dB
Drive Attenuation@2V Ref: AVmax, V
Drive Attenuation@0.25V Ref: AVmax, V
Absolute Gain Match@AVmax V12 = 4V, V
Gain Change Between Amplifiers V12 = 4V to 2V (Note 9) (Note 10)

=1VPP,f=10kHz 1 %

O

(Note 11) (Note 12) V

O

=4V

PP
PP

PP

=2V −6 dB

drive

= 0.25V −40 dB

drive

= 4V (Note 9)

drive

= 4V,

drive

±

0.3 dB

±

0.1 dB

2.8

3.4

PP
PP

7ns
7ns

MHz

200 ns

Width

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.
Note 2: Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications and

test conditions, see the 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.

Note 3: V
Note 4: Human body model, 100 pF discharged through a 1.5 kΩ resistor.
Note 5: Typical specifications are specified at +25˚C and represent the most likely parametric norm.
Note 6: Tested limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 7: The supply current specified is the quiescent current for V

depends on the output load. With video output at 1V DC, the additional current through V

Note 8: Output voltage is dependent on load resistor. Test circuit uses R
Note 9: Measure gain difference between any two amplifiers. V
Note 10: ∆A

gain change between any two amplifiers with the contrast voltage (V12) at either 4V or 2V measured relative to an A
max the three amplifiers’ gains might be 17.1 dB, 16.9 dB and 16.8 dB and change to 11.2 dB, 10.9 dB, and 10.7 dB respectively for V12 = 2V. This yields the
measured typical

Note 11: When measuring video amplifier bandwidth or pulse rise and fall times, a double sided full ground plane printed circuit board without socket is
recommended. Video amplifier 10 MHz isolation test also requires this printed circuit board. The reason for a double sided full ground plane PCB is that large
measurement variations occur in single sided PCBs.

Note 12: Adjust input frequency from 10 MHz (A
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
Note 14: During the AC tests the 4V DC level is the center voltage of the AC output signal. For example, if the output is 4 V

and 6V DC.
Note 15: Machine Model ESD test is covered by specification EIAJ IC-121-1981. A 200 pF cap is charged to the specified voltage, then discharged directly into the

IC with no external series resistor (resistance of discharge path must be under 50Ω).

supply pins 3, 11, 22, 23, 25 must be externally wired together to prevent internal damage during VCCpower on/off cycles.

CC

and V

CC1

= 635 mVPP.

track is a measure of the ability of any two amplifiers to track each other and quantifies the matching of the three attenuators. It is the difference in

V

±

0.1 dB channel tracking.

max reference level) to the −3 dB corner frequency (f

V

IN

IN

= 10 MHz for V

CC2

= 390Ω.

L

sep 10 MHz

with RL=∞, see

.

CC2

Figure 2

is 8 mA for

’s test circuit. The supply current for V

Figure 2

’s test circuit.

max condition, V12 = 4V. For example, at A

V

).

−3 dB

the signal will swing between 2V DC

PP

(pin 23) also

CC2

ns

ns

V

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Typical Performance Characteristics V

LM1208

Attenuation vs Contrast Voltage

= 12V, TA= 25˚C unless otherwise specified

CC

Attenuation vs Drive Voltage

DS100083-2

DS100083-3

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LM1208

Typical Performance Characteristics V

LM1208 Crosstalk vs Frequency

LM1208 Contrast vs Frequency

= 12V, TA= 25˚C unless otherwise specified (Continued)

CC

DS100083-4

LM1208 Drive vs Frequency

DS100083-5

DS100083-6

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Testing Circuit

LM1208

FIGURE 2. LM1208 DC Test Circuit

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DS100083-7

(Continued)

LM1208

FIGURE 3. LM1208 AC Test Circuit

DS100083-8

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