Datasheet

1. General description
The PCF2129 is a CMOS
1
Real Time Clock (RTC) and calendar with an integrated
Temperature Compensated Crystal (Xtal) Oscillator (TCXO) and a 32.768 kHz quartz
crystal optimized for very high accuracy and very low power consumption. The PCF2129
has a selectable I
2
C-bus or SPI-bus, a backup battery switch-over circuit, a
programmable watchdog function, a timestamp function, and many other features.
For a selection of NXP Real-Time Clocks, see Table 83 on page 75
2. Features and benefits
 Operating temperature range from 40 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 year
correction
 Timestamp function
 with interrupt capability
 detection of two different events on one multilevel input pin (for example, for tamper
detection)
 Two line bidirectional 400 kHz Fast-mode I
2
C-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 output
PCF2129
Accurate RTC with integrated quartz crystal for industrial
applications
Rev. 7 — 19 December 2014 Product data sheet
1. The definition of the abbreviations and acronyms used in this data sheet can be found in Section 20.