PCF2123_11 Datasheet, PDF (1/63 Pages) NXP Semiconductors – SPI Real time clock/calendar Time keeping application

PCF2123
SPI Real time clock/calendar
Rev. 5 — 27 April 2011
Product data sheet
1. General description
The PCF2123 is a CMOS¹ Real-Time Clock (RTC) and calendar optimized for low power
applications. Data is transferred serially via a Serial Peripheral Interface (SPI-bus) with a
maximum data rate of 6.25 Mbit/s. An alarm and timer function is also available providing
the possibility to generate a wake-up signal on an interrupt pin. An offset register allows
fine tuning of the clock.
2. Features and benefits
„ Real time clock provides year, month, day, weekday, hours, minutes, and seconds
based on a 32.768 kHz quartz crystal
„ Low backup current while running: typical 100 nA at V_DD = 2.0 V and T_amb = 25 °C
„ Resolution: seconds to years
„ Watchdog functionality
„ Freely programmable timer and alarm with interrupt capability
„ Clock operating voltage: 1.1 V to 5.5 V
„ 3 line SPI-bus with separate, but combinable data input and output
„ Serial interface at V_DD = 1.6 V to 5.5 V
„ 1 second or 1 minute interrupt output
„ Integrated oscillator load capacitors for C_L = 7 pF
„ Internal Power-On Reset (POR)
„ Open-drain interrupt and clock output pins
„ Programmable offset register for frequency adjustment
3. Applications
„ Time keeping application
„ Battery powered devices
„ Metering
„ High duration timers
„ Daily alarms
„ Low standby power applications
1. The definition of the abbreviations and acronyms used in this data sheet can be found in Section 21.