LM1246  Product Folder

The LM1246 pre-amp is an integrated CMOS CRT preamp. It has an I²C compatible interface which allows control of all the 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 LM1246 preamp is also designed to be compatible with the LM246x high gain driver family.

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.

The IC is packaged in an industry standard 24-lead DIP molded plastic package.

• Fully addressable 512 Character OSD, simiilar in features to the LM1237/LM1247, with selectable 2 byte character addressing or LM1247 bank select modes
• 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
• Internal 512 character RAM, which can be displayed as one single or two independent windows
• Enhanced I²C compatible microcontroller interface to allow versatile Page RAM access
• OSD Window Fade In/Fade Out
• OSD Half Tone Transparency
• Video Data dectection for Auto Centering & Sizing
• OSD override allows OSD messages to override video and the use of burn-in screens with no video output.
• 4 DAC outputs (8-bit resolution) for bus controlled CRT bias and brightness
• Spot killer which blanks the video outputs when V_CC falls below the specified threshold
• Suitable for use with discrete or integrated clamp, with software configurable brightness mixer
• 4-Bit Programmable start position for internal Horizontal Blanking
• Horizontal blanking and OSD synchronization directly from deflection signals. The blanking can be disabled, if desired.
• Vertical blanking and OSD synchronization directly from deflection signals. The blanking width is register programmable and can be disabled, if desired.
• Power Saving Mode with 65% power reduction
• Matched to LM246x driver and LM2479/80 bias IC's

• Low end 15" and 17" bus controlled monitors with OSD
• 1024x768 displays up to 85 Hz requiring OSD capability
• Very low cost systems with LM246x driver