PCF2003

PCF2003 32 kHz watch circuit with programmable adaptive motor pulse and pulse period Rev. 1.1 — 16 October 2019 Product data sheet 1. General description The PCF2003 is a CMOS integrated circuit for battery operated wrist watches with a 32 kHz quartz crystal as timing element and a bipolar 1 Hz stepping motor. The quartz crystal oscillator and the frequency divider are optimized for minimum power consumption. A timing accuracy of 1 ppm is achieved with a programmable, digital frequency adjustment. To obtain the minimum overall power consumption for the watch, an automatic motor pulse adaptation function is provided. The circuit supplies only the minimum drive current, which is necessary to ensure a correct motor step. Changing the drive current of the motor is achieved by chopping the motor pulse with a variable duty cycle. The pulse period and the range of the variable duty cycle can be programmed to suit different types of motors. The automatic pulse adaptation scheme is based on a safe dynamic detection of successful motor steps. A pad RESET is provided (used for stopping the motor) for accurate time setting and for accelerated testing of the watch. 2. Features and benefits  Amplitude-regulated 32 kHz quartz crystal oscillator, with excellent frequency stability and high immunity to leakage currents  Electrically programmable time calibration with 1 ppm resolution stored in One Time Programmable (OTP) memory  The quartz crystal is the only external component connect...