LM1238 Datasheet | National Semiconductor

Description The LM1238 pre-amp is an integrated, three channel video pre-amp. It has an I2C patible interface which allows control of all the parameters necessary to directly setup and adjust the gain and contrast in the CRT display. Four I2C patible DACs are available to control monitor bias and brightness circuits. The LM1238 preamp is designed to be 100% patible with the LM246x high gain driver family and the LM2479/80 Clamp ICs. Black level clamping of the video signal is carried out directly on the AC coupled input signal into the high impedance pre-amplifier inputs, 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 OSD override allows OSD messages to be displayed while blanking input video n Internally generated burn-in screen n 4 DAC outputs (8-bit resolution) for bus controlled CRT bias and brightness n Spot killer which blanks the video outputs when VCC falls below the specified threshold n Suitable for use with discrete or integrated clamp, with software configurable brightness mixer n H and V blanking (V blanking is optional and has register programmable width) n Power Saving Mode with 65% power reduction n Matched to LM246x driver and 2479/80 clamp Applications n Low end 15" and 17" bus controlled monitors with OSD n 1024x768 displays up to 85 Hz requiring OSD capability n Very low cost systems with LM246x driver Features n I2C patible microcontroller interface n Internal OSD generator with 16 sets of color icons Block and Connection Diagram FIGURE 1. Order Number LM1238AAC/NA See NS Package Number N24D © 2003 National Semiconductor Corporation DS200387 .national. Absolute Maximum Ratings (Notes 1, 3) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage, Pins 15 and 19...