May 2005
LM1276
150 MHz I2C Compatible RGB Preamplifier with Internal
512 Character OSD ROM, 512 Character RAM and 4
DACs
n Enhanced I2C compatible microcontroller interface to
allow versatile Page RAM access.
n OSD Window Fade In/Fade Out.
n OSD Variable Tone Transparency.
General Description
The LM1276 pre-amp is an integrated CMOS CRT preamp
with an integrated Hi-Brite Window generator, 512 Character
OSD generator, and an auto size measurement circuit. It has
n 3 Bit OSD Contrast.
an I2C compatible interface, which allows control of all the
n Video Data detection for Auto Centering & Sizing.
n 2 Bit Adjustable Burn-in screen Mode with no video
input.
n 4 DAC outputs (8-bit resolution) for bus controlled CRT
bias and brightness.
parameters necessary to directly setup and adjust the gain
and contrast in the CRT display. Brightness and bias can be
controlled through the DAC outputs, which are well matched
to the LM2479 and LM2480 integrated bias clamp ICs. The
LM1276 preamp is also designed to be compatible with the
LM247x high gain driver family.
n Spot killer, which blanks the video outputs when VCC
falls below the specified threshold.
Black level clamping of the video signal is carried out directly
on the AC coupled input signal into the high impedance
preamplifier input, thus eliminating the need for additional
clamp capacitors. Horizontal and vertical blanking of the
outputs is provided. Vertical blanking is optional and its
duration is register programmable.
n Suitable for use with discrete or integrated clamp, with
software configurable brightness mixer.
n Programmable ABL Onset for Multi-Limit Applications.
n 4-Bit Programmable start position for internal Horizontal
Blanking.
The IC is packaged in an industry standard 28-lead narrow
DIP molded plastic package.
n Horizontal blanking and OSD synchronization directly
from deflection signals. The blanking can be disabled, if
desired.
n Vertical blanking and OSD synchronization directly from
sync signals. The blanking width is register
programmable and can be disabled, if desired.
n Power Saving Mode with 65% power reduction.
n Matched to LM246x, LM247x drivers, and LM2479/80
bias IC’s.
Features
n Integrated Hi-Brite Window Generator operation
independent of the Microcontroller.
n Programmable Video Emphasis Control.
n 8 Programmable Hi-Brite Windows.
n Hi-Brite Enhancement on full screen, window only, or
outside of windows.
Applications
n Fully addressable 512 Character OSD.
n Internal 512 character OSD ROM usable as either (a)
384 2-color plus 128 4-color characters, (b) 640 2-color
characters, or (c) some combination in between.
n Internal 512 character RAM.
n Ideal preamplifier IC for total Hi-Brite Solution.
n 17" and 19” bus controlled monitors with OSD.
n Low cost systems with LM247x drivers.
© 2005 National Semiconductor Corporation
DS200969
www.national.com