PCF2003DUS: 32 kHz watch circuit with programmable adaptive motor pulse and pulse period

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.

Data Sheets (1)
Name/DescriptionModified Date
32 kHz watch circuit with programmable adaptive motor pulse and pulse period (REV 1.0) PDF (246.0 kB) PCF200320 Oct 2015
Packing (1)
Name/DescriptionModified Date
PCF2003DUS; Reel dry pack, SMD, 7" Q1/T1 standard product orientation Orderable part number ending ,012 or... (REV 1.1) PDF (272.0 kB) WLCSP8_PCF2003DUS_01225 Nov 2015
Ordering Information
ProductStatusPackage versionApplicationFunction
PCF2003DUSEnd of LifeNAU000
PCF2003DUS/DANo Longer ManufacturedNAU000
Package Information
Product IDPackage DescriptionOutline VersionReflow/Wave SolderingPackingProduct StatusPart NumberOrdering code(12NC)MarkingChemical ContentRoHS / Pb Free / RHFLeadFree Conversion DateMSLMSL LF
PCF2003DUS/DAReel 7" Q1/T1 in DrypackDiscontinuedPCF2003DUS/DAAZ (9353 062 43012)Standard MarkingPCF2003DUS/DAAlways Pb-freeNANA
Reel 7" Q1/T1 in DrypackWithdrawnPCF2003DUS/DAZ (9353 062 43027)Standard MarkingPCF2003DUS/DAAlways Pb-freeNANA