An I/sup 2/L watch chip with direct LED drive

A three function watch circuit using I/SUP 2/L technology has been fabricated on a chip measuring 86 mils/spl times/96 mils. The circuit draws 7-10 /spl mu/A in the run mode and has on-chip segment and digit drivers which are capable of sourcing 15 mA and sinking up to 70 mA, respectively. The low frequency (<1 kHz) transistors in this circuit operate with 5-10 nA base current. A unique four-base divide-by-two circuit, using current starving to implement delays, is the building block for the circuit and its small size (13 mil/SUP 2/) contributes to the small chip size. Segment and digit drivers which draw only 50 nA each in the run mode (no display) also contribute to the low chip current.