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.
The PCA148x series devices are CMOS integrated circuits specially suited for battery-operated, quartz-crystal-controlled wrist-watches with a bipolar stepping motor. The circuit includes a 32 kHz oscillator and provides an output capable of driving various types of bipolar stepping motors.
A key feature is the adaptive motor pulse technology, which reduces motor current consumption by up to 50% through self-adaptation of the motor pulse width based on the required torque. The device also features time calibration via EEPROM, battery end-of-life indication, and a stop function for accurate timing.
A quartz crystal is the only external component required for operation.
The waveform is produced in bursts of 4 pulses every 4 seconds to indicate this condition.
Stage 6 is implemented for a maximum of 8 minutes with no attempt to keep current consumption low.