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PCA2003U: 32 kHz watch circuit with programmable adaptive motor pulse and pulse period

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.

PCA2003U: Product Block Diagram

Data Sheets (1)

Application Notes (3)

Users Guides (1)

Ordering Information

Package Information

Product ID	Package Description	Outline Version	Reflow/Wave Soldering	Packing	Product Status	Part NumberOrdering code(12NC)	Marking	Chemical Content	RoHS / Pb Free / RHF	LeadFree Conversion Date	IFR(FIT)	MTBF(hour)	MSL	MSL LF
PCA2003U/10AC/1				Wafer, Sawn on FFC, Non-Conductive	Active	PCA2003U/10AC/1,00 (9352 895 61005)	Standard Marking	PCA2003U/10AC/1		Always Pb-free	5	2E8	NA	NA