2003 Dec 17

2

Philips Semiconductors

Product specification

32 kHz watch circuit with programmable

adaptive motor pulse

PCA2000; PCA2001

FEATURES

• 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

connected

• Very low power consumption, typical 90 nA

• One second output pulses for bipolar stepping motor

• Minimum power consumption for the entire watch, due

to self adaptation of the motor drive according to the

required torque

• Reliable step detection circuit

• Motor pulse width, pulse modulation, and pulse

adaptation range programmable in a wide range, stored

in OTP memory

• Stop function for accurate time setting and power saving

during shelf life

• End Of Life (EOL) indication for silver oxide or lithium

battery (only the PCA2000 has the EOL feature)

• Test mode for accelerated testing of the mechanical

parts and the IC.

APPLICATIONS

• Driver circuits for bipolar stepping motors

• High immunity motor drive circuits.

GENERAL DESCRIPTION

The PCA2000; PCA2001 are CMOS integrated circuits 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 width and the range of the variable duty cycle can be

programmed to suit different types of motor. 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.

The PCA2000 has a battery EOL warning function. If the

battery voltage drops below the EOL threshold voltage

(which can be programmed for silver oxide or lithium

batteries), the motor steps change from one pulse per

second to a burst of four pulses every 4 seconds.

The PCA2001 uses the same circuit as the PCA2000, but

without the EOL function.

ORDERING INFORMATION

TYPE NUMBER

PACKAGE

NAME

DESCRIPTION

VERSION

PCA2000U/AA

−

bare die; chip in tray

−

PCA2001U/AA

−

bare die; chip in tray

−

PCA2000U/10AA

−

bare die; chip on film frame carrier

−

PCA2001U/10AA

−

bare die; chip on film frame carrier

−