The HD66727, dot-matrix liquid crystal display controller and driver LSI incorporating a key scan function, displays alphanumerics, katakana, hiragana, and symbols. It can be configured to drive a dotmatrix liquid crystal display and control key scan functions under the control of an I2C bus or a clocksynchronized serial microprocessor. A single HD66727 is capable of displaying up to four 12-character lines, 40 segments, and 12 annunciators, and controlling up to a 4-by-8 key matrix, and driving three LED. The HD66727 incorporates all the functions required for driving a dot-matrix liquid crystal display such as display RAM, character generator, and liquid crystal drivers, and it also incorporates a booster for the LCD power supply and key scan functions. The HD66727 provides various functions to reduce the power consumption of an LCD system such as lowvoltage operation of 2.4V or less, a booster for generating a maximum of triple LCD drive voltage from the supplied voltage, and voltage-followers for decreasing the direct current flow in the LCD drive bleederresistors. Combining these hardware functions with software functions such as standby and sleep modes allows a fine power control. The HD66727, with the above functions, is suitable for any portable batterydriven product requiring long-term driving capabilities and small size.