LM1281N National Semiconductor, LM1281N Datasheet

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LM1281N

Manufacturer Part Number
LM1281N
Description
IC VIDEO AMP SYSTEM 28-DIP
Manufacturer
National Semiconductor
Datasheet

Specifications of LM1281N

Applications
General Purpose
Number Of Circuits
3
-3db Bandwidth
85MHz
Current - Supply
95mA
Current - Output / Channel
28mA
Voltage - Supply, Single/dual (±)
11.4 V ~ 12.6 V
Mounting Type
Through Hole
Package / Case
28-DIP (0.600", 15.24mm)
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Other names
*LM1281N

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© 1999 National Semiconductor Corporation
LM1281
85 MHz RGB Video Amplifier System with On Screen
Display (OSD)
General Description
The LM1281 is a full feature video amplifier with OSD inputs,
all within a 28-pin package. This part is intended for use in
monitors with resolutions up to 1024 x 768. The video sec-
tion of the LM1281 features three matched video amplifiers
with blanking. All of the video amplifier adjustments feature
high input impedance 0V to 4V DC controls, providing easy
interfacing to bus controlled alignment systems. The OSD
section features three TTL inputs and a DC contrast control.
The switching between the OSD and video section is con-
trolled by a single TTL input. Although the OSD signals are
TTL inputs, these signals are internally processed to match
the OSD logic low level to the video black level. When ad-
justing the drive controls for color balance of the video sig-
nal, the color balance of the OSD display will track these
color adjustments. The LM1281 also features an internal
spot killer circuit to protect the CRT when the monitor is
turned off. For applications without OSD insertion please re-
fer to the LM1205 or LM1208 data sheets.
Features
n Three wideband video amplifiers 85 MHz
Block and Connection Diagram
(4 V
PP
output)
DS012355
FIGURE 1. Order Number LM1281N
@
See NS Package Number N28B
−3 dB
n TTL OSD inputs, 50 MHz bandwidth
n On chip blanking, outputs under 0.1 V when blanked
n High speed Video/OSD switch
n Independent drive control for each channel for color
n 0V to 4V, high impedance DC contrast control with over
n 0V to 4V, high impedance DC drive control (0 dB to
n 0V to 4V, high impedance DC OSD contrast control with
n Capable of 7 V
n Output stage directly drives most hybrid or discrete CRT
Applications
n High resolution RGB CRT monitors requiring OSD
balance
40 dB range
−12 dB range)
over 40 dB range
bandwidth)
drivers
capability
PP
output swing (slight reduction in
www.national.com
April 1999
DS012355-1

Related parts for LM1281N

LM1281N Summary of contents

Page 1

... Capable output swing (slight reduction in PP bandwidth) n Output stage directly drives most hybrid or discrete CRT drivers Applications n High resolution RGB CRT monitors requiring OSD capability @ −3 dB FIGURE 1. Order Number LM1281N See NS Package Number N28B April 1999 DS012355-1 www.national.com ...

Page 2

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage Pins 6, 9, and 22 Peak Video Output Source Current (Any One Amp) Pins 18, 20, and 23 Voltage at Any Input Pin ( Power Dissipation (P ...

Page 3

AC Electrical Characteristics = 25˚C, V See AC Test Circuit ( Figure for the AC test unless otherwise stated (Note 15) Symbol Parameter A Video Amplifier Gain V max A Contrast Attenuation @ 2V ...

Page 4

OSD Electrical Characteristics = 25˚C; V See DC Test Circuit ( Figure unless otherwise stated 0V Symbol Parameter V OSD Input Low Input Voltage OSDI V OSD Input High Input Voltage OSDh ...

Page 5

Typical Performance Characteristics Attenuation vs Contrast Voltage DS012355-2 LM1281 Crosstalk vs Frequency LM1281 Contrast vs Frequency = 12V 25˚C unless otherwise specified Attenuation vs Drive Voltage LM1281 Drive vs Frequency DS012355-4 DS012355-5 5 DS012355-3 DS012355-6 ...

Page 6

Timing Diagrams FIGURE 2. Blanking Propagation Delay and Rise/Fall Time FIGURE 3. Video to OSD, OSD to Video Propagation Delay and Switching Time www.national.com DS012355-7 DS012355-8 6 ...

Page 7

Timing Diagrams (Continued) FIGURE 4. OSD Propagation Delay and Rise/Fall Times Test Circuits FIGURE 5. LM1281 OSD Video Preamp DC Test Circuit DS012355-9 7 DS012355-10 www.national.com ...

Page 8

Test Circuits (Continued) FIGURE 6. LM1281 OSD Video Preamp AC Test Circuit www.national.com 8 DS012355-11 ...

Page 9

Test Circuits (Continued) FIGURE 7. LM1281 OSD Video Preamp Demonstration Board Schematic 9 DS012355-12 www.national.com ...

Page 10

Pin Descriptions Pin No. Pin Name 1 Red OSD Input 2 Green OSD Input 3 Blue OSD Input 4 Video/OSD Switch 5 Red Video In 8 Green Video In 11 Blue Video CC1 9 7 Ground 10 ...

Page 11

Pin Descriptions (Continued) Pin No. Pin Name 18 Blue Video Out 20 Green Video Out 23 Red Video Out 22 V CC2 25 RGB Cutoff Adjust Functional Description Figure 1 on the front page shows the block diagram of the ...

Page 12

Functional Description couple the preamp output to the cathode drivers. Therefore only one cutoff adjustment is provided, this is used primarily to optimize the operation of the cathode drivers. Note that the Blank and Clamp Gates are active low. These ...

Page 13

... References Zahid Rahim, “Guide to CRT Video Design,” Application Note 861, National Semiconductor Corp., Jan. 1993 Ott, Henry W. Noise Reduction Techniques in Electronic sys- tems , John Wiley & Sons, New York, 1976 13 www.national.com ...

Page 14

... NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant ...

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