1.General descriptionThe PCF2129 is a CMOS1 Real Time Clock (RTC) and calendar with an integratedTemperature Compensated Crystal (Xtal) Oscillator (TCXO) and a 32.768 kHz quartzcrystal optimized for very high accuracy and very low power consumption. The PCF2129has a selectable I2C-bus or SPI-bus, a backup battery switch-over circuit, aprogrammable watchdog function, a timestamp function, and many other features.For a selection of NXP Real-Time Clocks, see Table 83 on page 752.Features and benefits Operating temperature range from40 C to 85 C Temperature Compensated Crystal Oscillator (TCXO) with integrated capacitors Typical accuracy: PCF2129AT:3 ppm from 15 C to 60 C PCF2129T:3 ppm from 30 C to 80 C Integration of a 32.768 kHz quartz crystal and oscillator in the same package Provides year, month, day, weekday, hours, minutes, seconds, and leap yearcorrection Timestamp function with interrupt capability detection of two different events on one multilevel input pin (for example, for tamperdetection) Two line bidirectional 400 kHz Fast-mode I2C-bus interface 3 line SPI-bus with separate data input and output (maximum speed 6.5 Mbit/s) Battery backup input pin and switch-over circuitry Battery backed output voltage Battery low detection function Power-On Reset Override (PORO) Oscillator stop detection function Interrupt output (open-drain) Programmable 1 second or 1 minute interrupt Programmable watchdog timer with interrupt Programmable alarm function with interrupt capability Programmable square outputPCF2129Accurate RTC with integrated quartz crystal for industrialapplicationsRev. 7 — 19 December 2014Product data sheet1.The definition of the abbreviations and acronyms used in this data sheet can be found in Section 20.
