A monolithic optoelectronic IC carring out the function of a smart sensor for control and monitoring is described. The 2.3x2.3 mm(2) chip was fabricated with a 2-mum CMOS/SOS process technology. It consists of built-in solar cell voltage source, photo-voltaic sensor, CMOS A/D converter, EEPROM, decoder, linear amplifier, output buffer. The IC provides the stable operation for light intensity from 1500lk to more than 10(6) Ik and controls the loads with Output voltage 2.5...3.5V and power 6...8 muW.