PCA2000U 32 kHz watch circuit with programmable adaptive motor pulse

The PCA2000 and 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 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.

The PCA2000 has a battery End Of Life (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

产品特点 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 of the watch and the IC
Test bits for type recognition

应用

Driver circuits for bipolar stepping motors
High immunity motor drive circuits

封装

型号	可订购的器件编号	订购码 (12NC)	产品状态	封装
PCA2000U/10AC/1	9352 895 57005	PCA2000U/10AC/1,00	量产
PCA2000U/AC/1	9352 895 56026	PCA2000U/AC/1,026	量产

订货和供应

型号	订购码 (12NC)	可订购的器件编号	化学成分
PCA2000U/10AC/1	9352 895 57005	PCA2000U/10AC/1,00	PCA2000U/10AC/1
PCA2000U/AC/1	9352 895 56026	PCA2000U/AC/1,026	PCA2000U/AC/1

PCA2000U 技术支持

档案名称	标题	类型	格式
PCA2000U	32 kHz watch circuit with programmable adaptive motor pulse	Data sheet	pdf
AN10706	Handling bare die	Application note	pdf
AN10853	ESD and EMC sensitivity of IC	Application note	pdf
UM10569	Store and transport requirements	User manual	pdf