LM1237  Product Folder

The LM1237 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 LM1237 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.

• I²C compatible microcontroller interface
• Internal 254 character OSD usable as either (a) 190 2-color plus 64 4-color characters, (b) 318 2-color characters, or (c) some combination in between.
• OSD override allows OSD messages to override video and the use of burn-in screens with no video input
• 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
• H and V blanking (V blanking is optional and has register programmable width)
• Power Saving Mode with 80% power reduction
• Matched to LM246x driver and LM2479/80 drivers

• 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