PHILIPS PCA148x series 32 kHz watch circuits with adaptive motor pulse handbook
Datasheet
The PCA148x series is a 32kHz watch circuit with adaptive motor pulse. It features a 32kHz oscillator with amplitude regulation and excellent frequency stability, high immunity of the oscillator to leakage currents. The time calibration is electrically programmable and reprogrammable via EEPROM, and only requires a quartz crystal as the external component. It has very low current consumption, typically 170nA. It has an output for bipolar stepping motors of different types and achieves up to 50% reduction in motor current compared with conventional circuits by self adaption of the motor pulse width according to the required torque of the motor. It has on-chip detection of the induced motor voltage to prevent loss of motor steps. It also includes indication for battery end-of-life, stop function for accurate timing, power-on reset for fast testing, and various test modes for testing the mechanical parts of the watch and the IC.