This is another common device people use everyday, in which a circuit drives the motor found in our watches or clocks to determine the time.
The circuit is mainly operated by PCA1462U IC, specially suited for battery-operated quartz-crystal controlled wrist watches. The quartz crystal is used to input an oscillated signal to the PCA1462U IC then produces an output of pulses that drives the stepping motor ON.
The IC used in this circuit is specialized for this application featuring an amplitude regulated 32KHz oscillator, with excellent frequency stability resulting in a high immunity from oscillator-to-leakage currents. The loss of motor steps is not possible because of an on-chip detection on the induced motor voltage, this output is applicable for different types of bipolar stepping motors. This IC also has a very low current consumption; typically 170 nA, and the time calibration of the pulses is electrically programmable and reprogrammable (via EEPROM).
- PCA1462U CMOS integrated circuit
- 1.55V dc power source
- Quartz Crystal Oscillator
- Stepper Motor
Quartz-crystal Controlled Wrist Watch – [Link]