General description

The PCF2131 is a CMOS 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 ultra low power consumption. The

PCF2131 has a selectable I2C-bus or SPI-bus, a backup battery switch-over circuit, a

programmable watchdog function, four timestamps function, and many other features.

Features and benefits

? Operating temperature range from -40 °C to +85 °C

? Temperature Compensated Crystal Oscillator (TCXO) with trimmed integrated

capacitors

? Ultra low supply current: typical 64 nA at VDD = 3.3 V

? Temperature compensated RTC, typical accuracy ±3 ppm from -40 °C to +85 °C

? Integration of a 32.768 kHz quartz crystal and oscillator in the same package

? Provides year, month, day, weekday, hours, minutes, seconds and 1/100 seconds

? Provides leap year correction

? Timestamp function

– with interrupt capability

– detection of four different events on four input pins (for example, for tamper detection)

? 2-line bidirectional 400 kHz Fast-mode I2C-bus interface

? 4-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 (POR)

? Power-On Reset Override (PORO) function

? Software reset function

? Two interrupt outputs (open-drain)

? Programmable 1 second or 1 minute interrupt

? Programmable watchdog timer with interrupt

? Programmable alarm function with interrupt capability

? Programmable square output

? Clock operating voltage: 1.2 V to 5.5 V

Applications

? Electronic metering for electricity, water, and gas

? Precision timekeeping

? Access to accurate time of the day

? GPS equipment to reduce time to first fix

? Applications that require an accurate process timing

? Products with long automated unattended operation time