GENERAL DESCRIPTION

The PCA146x series devices are CMOS integrated circuits specially suited for battery-operated, quartz-crystal-controlled wrist-watches, with a bipolar stepping motor.

FEATURES

• 32 kHz oscillator, amplitude regulated with excellent frequency stability

• High immunity of the oscillator to leakage currents

• Time calibration electrically programmable and reprogrammable (via EEPROM)

• A quartz crystal is the only external component required

• Very low current consumption; typically 170 nA

• Output for bipolar stepping motors of different types

• Up to 50% reduction in motor current compared with conventional circuits, by self adaption of the motor pulse width to match the required torque of the motor

• No loss of motor steps possible because of on-chip detection of the induced motor voltage

• Detector for lithium or silver-oxide battery voltage levels

• Indication for battery end-of-life

• Stop function for accurate timing

• Power-on reset for fast testing

• Various test modes for testing the mechanical parts of the watch and the IC.