NSC LM1279N, LM1279AN Datasheet

LM1279
110 MHz RGB Video Amplifier System with OSD

General Description

The LM1279 is a full featured and low cost video amplifier
with OSD (On Screen Display). 8V operation for low power
and increased reliability. Supplied in a 20-pin DIP package,
accommodating very compact designs of the video channel
requiring OSD. All video functions controlled by 0V to 4V
high impedance DC inputs. This provides easy interfacing to
5V DACs used in computer controlled systems and digital
alignment systems. Unique OSD switching, no OSD switch­ing signalrequired.An OSDsignal at any OSD inputtypically
switches the LM1279 to the OSD mode within 5 ns. Ideal
video amplifier for the low cost OSD monitor with resolutions
up to 1280 x1024. The LM1279 provides superior protection
against ESD. Excellent alternative for the MC13282 in new
designs.

Features

n Three wideband video amplifiers 110 MHz@−3dB (4

V

PP

output)

n OSD signal to any OSD input pin automatically switches

all 3 outputs to the OSD mode

n Fast OSD switching time, typically 5 ns
n 3.5 kV ESD protection
n Fixed cutoff level typically set to 1.35V
n 0V to 4V, high impedance DC contrast control with over

40 dB range

n 0V to 4V, high impedance DC drive control (0 dB to

−12 dB range)

n Matched (

±

0.3 dB or 3.5%) attenuators for contrast

control

n Output stage directly drives CRT drivers
n Ideal combination with LM2407 CRT driver

Applications

n High resolution RGB CRT monitors
n Video AGC amplifiers
n Wideband amplifiers with contrast and drive controls
n Interface amplifiers for LCD or CCD systems

Block and Connection Diagram

DS100091-1

FIGURE 1. Order Number LM1279N

See NS Package Number N20A

September 1998

LM1279 110 MHz RGB Video Amplifier System with OSD

© 1998 National Semiconductor Corporation DS100091 www.national.com

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

Pins 2 and 16 (Note 3) 10V

Peak Video Output Source Current

(Any One Amp) Pins 13, 15, or 18 28 mA

Voltage at Any Input Pin (V

IN

)V

CC

≥ VIN≥ GND

Power Dissipation (P

D

)

(Above 25˚C Derate Based on θ

JA

and TJ) 2.1W

Thermal Resistance to Ambient (θ

JA

) 60˚C/W

Thermal Resistance to Case (θ

JA

) 37˚C/W

Junction Temperature (T

J

) 150˚C
ESD Susceptibility (Note 4) 3.5 kV
ESD Machine Model (Note 16) 300V
Storage Temperature −65˚C to 150˚C
Lead Temperature

(Soldering, 10 sec.) 265˚C

Operating Ratings (Note 2)

Temperature Range 0˚C to 70˚C

Supply Voltage (V

CC

)

7.5V ≤ V

CC

≤

8.5V

DC Electrical Characteristics

TA= 25˚C; V

CC1=VCC2

= 8V; V10= 4V; V

Drive

= 4V; V11= 7V; V

OSD

= 0V; RL= 390Ω unless otherwise stated.

Symbol Parameter Condition

Typical

(Note 5)

Limit

(Note 6)

Units

I

S

Supply Current I

CC1+ICC2−ILoad

(Note 7) 80 90 mA(max)

V

3, 5, 8

Video Amplifier Input Bias Voltage 2.5 V

R

IN

Video Input Resistance Any One Amplifier 20 kΩ

V

11off

Sandcastle Off Voltage 1.4 1.2 V (max)

V

11blank

Sandcastle Blank Voltage Start of Blank Region 1.4 1.7 V (min)

V

11blank

Sandcastle Blank Voltage End of Blank Region 2.8 3.2 V (max)

V

11clamp &

Blank

Sandcastle Clamp and Blank On
Voltage

Start of Clamp and Blank
Region

3.2 3.6 V (min)

V

11clamp &

Blank

Sandcastle Clamp and Blank On
Voltage

End of Clamp and Blank
Region

6.2 5.8 V (max)

V

11clamp

Sandcastle Clamp On/Blank Off
Voltage

Clamp Only Region, Max =
V

CC

6.2 6.5 V (min)

I

11off

Sandcastle Off Current V11= 0V −5.0 −8.0 µA(max)

I

11test

Sandcastle Clamp On/Blank Off
Curr

V11= 6.5V

−100 −500 nA(max)

I

clamp

Clamp Cap Charge Current Clamp Comparators On

±

750

±

500 µA(min)

I

bias

Clamp Cap Bias Discharge
Current

Clamp Comparators Off

50 200 nA (max)

V

OL

Video Black Level V

Video in

= 0V, V11= 6.5V 1.35 1.55 V (max)

∆V

OL

Video ∆Black Level Output
Voltage

Between Any Two Amplifiers

±

50

±

200 mV (max)

V

OH

Video Output High Voltage V

11

<

1.2V 5.0 4.6 V (min)

I

10, 12, 14, 17

Contrast/Drive Control Input
Current

V

Contrast=VDrive

=0Vto4V

−0.25 −1.5 µA (max)

I

1l, 19l, 20l

OSD Low Input Current (each) V

OSD in

= 0V −2.5 −10.0 µA(max)

I

1h, 19h, 20h

OSD High Input Current (each) V

OSD in

= 5V 100 130 µA(max)

V

OL

(Blank) Video Output during Blanking V11= 1.7V 0.1 0.5 V (max)

AC Electical Characteristics

TA= 25˚C; V

CC1=VCC2

= 8V. Manually adjust Video Output pins 13, 15, and 18 to 4V DC for the AC test unless otherwise

stated. (Note 15)

Symbol Parameter Conditions

Typical

(Note 5)

Limit

(Note 6)

Units

A

Vmax

Video Amplifier Gain V10= 4V, VIN= 635 mV

PP

6.8 5.9 V/V (min)

V

drive

= 4V 16.7 15.4 dB (min)

∆A

V2V

Contrast Attenuation@2V Ref: AVmax, V10=2V −6 dB

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AC Electical Characteristics (Continued)

TA= 25˚C; V

CC1=VCC2

= 8V. Manually adjust Video Output pins 13, 15, and 18 to 4V DC for the AC test unless otherwise

stated. (Note 15)

Symbol Parameter Conditions

Typical

(Note 5)

Limit

(Note 6)

Units

∆A

V 0.25V

Contrast Attenuation@0V Ref: AVmax, V10= 0V −35 dB

∆Drive Drive Control Range V

drive

=0Vto4V,V10=4V 12 dB

A

V match

Absolute Gain Match@AVmax V10= 4V, V

drive

= 4V (Note 9)

±

0.3 dB

A

V track

Gain Change Between Amplifiers V10= 4V to 2V (Notes 9, 10)

±

0.3 dB

f(−3 dB) Video Amplifier Bandwidth V

10

= 4V, V

drive

= 4V,

110 MHz

(Notes 11, 12)) V

O

= 3.5 V

P-P

tr(Video) Video Output Rise Time VO= 3.5 V

P-P

(Note 11) 3.6 ns

t

f

(Video) Video Output Fall Time VO= 3.5 V

P-P

(Note 11) 3.2 ns

V

sep

10 kHz Video Amplifier 10 kHz Isolation V10= 4V (Note 13) −70 dB

V

sep

10 MHz Video Amplifier 10 MHz Isolation V10= 4V (Notes 11, 13) −50 dB

∆V

OL

(OSD) OSD Black Level, Difference from

Video Black Level

V

OSD in

= 0.8V, OSD Mode

−0.4 −0.7 V (max)

V

OH

(OSD) OSD Output High Voltage (above

measured video black level)

V

OSD in

= 2.5V, OSD Mode

2.1 2.4 V (max)

t

r

(OSD) Going into OSD Mode OSD Mode (

Figure 2

) 5.0 ns

t

f

(OSD) Going out of OSD Mode OSD Mode (

Figure 2

) 10.0 ns

t

r-prop

(OSD) Starting OSD Propagation Delay Switching to OSD Mode (

Figure 3

) 13.0 ns

t

f-prop

(OSD) Ending OSD Propagation Delay Switching to Vid. Mode (

Figure 3

) 14.0 ns

T

pw

(Clamp) Input Clamp Pulse Width (Part of

Sandcastle Sync)

(Note 14)

200 ns (min)

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.
Note 2: Operating Ratings indicate conditionsfor which the device is functional, butdo not guarantee specific performance limits. Forguaranteed 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

CC

supply pins 2 and 16 must be externally wired together to prevent internal damage during VCCpower on/off cycles.

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 current for V

CC1

and V

CC2

minus the current through RL(I

supply=ICC1+ICC2−IL

). The supply current for V

CC2

(pin 16)

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

CC2

is 7.7 mA with RL= 390Ω.

Note 8: Output voltage is dependent on load resistor. Test circuit uses R

L

= 390Ω.

Note 9: Measure gain difference between any two amplifiers. V

IN

= 635 mVPP.

Note 10: ∆A

V

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

gain change between any two amplifiers with the contrast voltage (V

10

) at either 4V or 2V measured relative to an AVmax condition, V10= 4V. For example, at A

V

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 V10= 2V. This yields the mea­sured typical

±

0.1 dB channel tracking.

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

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 othertwo undriven amplifiers relative to the driven amplifier to determine channelseparation. 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.

Note 15: During theAC test the 4V DC level is the center voltage of the AC output signal. For example, if the output is 4 V

PP

the signal will swing between 2V DC

and 6V DC.
Note 16: 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).

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Timing Diagrams

DS100091-2

FIGURE 2. OSD Rise and Fall Times

DS100091-3

FIGURE 3. OSD Propagation Delays

DS100091-4

FIGURE 4. Sandcastle Sync Pulse

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Test Circuits

DS100091-5

**Note: All video inputs

must

have a series 30Ω resistor for protection against EOS (Electrical Over Stress). If the OSD signals are external to the monitor, or

these signals are present any time when +8V is not fully powered up, then the OSD inputs also

require

a series 30Ω resistor.

FIGURE 5. LM1279 OSD Video Pre-amp Demonstration Board Schematic

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