LM1238 110 MHz I2C Compatible RGB Preamplifier with Internal Simple OSD Generator and 4 DACs General Description The LM1238 pre-amp is an integrated, three channel video pre-amp. 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. Four I2C compatible DACs are available to control monitor bias and brightness circuits. The LM1238 preamp is designed to be 100% compatible 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.