Survey of circuitry for wristwatches

Circuit requirements, as well as practical realizations, are discussed for different types of electronic wristwatches, namely, the spring-balance, tuning-fork, and quartz-crystal-controlled movements. Particular emphasis is placed on the oscillator, frequency divider, and motor-drive circuits for quartz watches. Bipolar integrated circuits are well adapted for oscillators and motor-drive circuits producing high current pulses (1 mA). Bipolar frequency dividers with adequate power consumption are possible up to approximately 32 kHz. Complementary MOS circuits offer the important advantages of low consumption and high density of integration. This technology presently appears to be a good solution for advanced watch designs using higher frequency quartz and electronic display systems. The discussion includes a general view of the evolution in this area. For this purpose references are given.