PCA2003_09 Datasheet, PDF (1/21 Pages) NXP Semiconductors – 32 kHz watch circuit with programmable adaptive motor pulse and pulse period

PCA2003
32 kHz watch circuit with programmable adaptive motor pulse
and pulse period
Rev. 02 — 21 July 2009
Product data sheet
1. General description
The PCA2003 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
I Amplitude-regulated 32 kHz quartz crystal oscillator, with excellent frequency stability
and high immunity to leakage currents
I Electrically programmable time calibration with 1 ppm resolution stored in One Time
Programmable (OTP) memory
I The quartz crystal is the only external component connected
I Very low supply current, typical 90 nA
I One second output pulses for bipolar stepping motor
I Five different programmable output periods (1 s to 30 s)
I Minimum power consumption for the entire watch, due to self adaptation of the motor
drive according to the required torque
I Reliable step detection circuit
I Motor pulse width, pulse modulation, and pulse adaptation range programmable in a
wide range, stored in OTP memory
I Stop function for accurate time setting and power saving during shelf life
I Test mode for accelerated testing of the mechanical parts of the watch and the IC
I Test bits for type recognition