PCF2127: Accurate RTC with 512 byte RAM and battery backup – selectable I²C-bus or SPI

Overview

The PCF2127 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 very low power consumption. The PCF2127 has 512 bytes of general-purpose static RAM, a selectable I²C-bus or SPI-bus, a backup battery switch-over circuit, a programmable watchdog function, a timestamp function, and many other features.

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Features

UL Recognized Component
Operating temperature range from -40 °C to +85 °C
Temperature Compensated Crystal Oscillator (TCXO) with integrated capacitors
Typical accuracy:
- PCF2127AT: ±3 ppm from -15 °C to +60 °C
- PCF2127T: ±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
512 bytes of general-purpose static RAM
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 wave output pin
Programmable countdown timer with interrupt
Clock operating voltage: 1.8 V to 4.2 V
Low supply current: typical 0.70 μA at V_DD = 3.3 V

Target 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

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Features

UL Recognized Component
Operating temperature range from -40 °C to +85 °C
Temperature Compensated Crystal Oscillator (TCXO) with integrated capacitors
Typical accuracy:
- PCF2127AT: ±3 ppm from -15 °C to +60 °C
- PCF2127T: ±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
512 bytes of general-purpose static RAM
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 wave output pin
Programmable countdown timer with interrupt
Clock operating voltage: 1.8 V to 4.2 V
Low supply current: typical 0.70 μA at V_DD = 3.3 V