General description
●The PCF2129T is a CMOS1 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 PCF2129T has a selectable I2C-bus or SPI-bus, a backup battery switch-over circuit, a programmable watchdog function, a timestamp function, and many other features.
●Features and benefits
●■ Temperature Compensated Crystal Oscillator (TCXO) with integrated capacitors
●■ Typical accuracy: ±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 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
●■ Extra power fail detection function with input and output pins
●■ 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
●■ Clock operating voltage: 1.8 V to 4.2 V
●■ Low supply current: typical 0.70 μA at VDD = 3.3 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