NXP PCF8523 Real-Time Clock (RTC) & Calendar IC, I2C, SOIC-8

The NXP PCF8523 is a CMOS real-time clock (RTC) and calendar IC engineered for exceptional accuracy and minimal power consumption, making it the perfect timekeeping solution for a vast array of electronic applications. Data transfer is handled efficiently via a fast I2C-bus interface, supporting data rates up to 1000 kbit/s, facilitating seamless communication with microcontrollers and other digital systems.

Featuring comprehensive alarm and timer functions, this RTC can generate a wake-up signal on an interrupt pin, enabling smart power management in battery-powered designs. A key asset is its integrated backup battery switch-over circuit, which automatically detects main power failure and seamlessly switches to a backup battery supply, ensuring uninterrupted timekeeping.

The clock provides precise tracking of year, month, day, weekday, hours, minutes, and seconds, all based on a stable 32.768 kHz quartz crystal. It includes an oscillator stop detection function and an internal power-on reset (POR) for reliable operation. Engineers can fine-tune the clock's accuracy using the programmable offset register for frequency adjustment.

Designed with flexibility in mind, it offers selectable integrated oscillator load capacitors and open-drain interrupt or clock output pins. With an ultra-low backup current and a wide operating voltage range, this component is a cornerstone for reliable, long-term timekeeping in demanding environments.

Specifications

• Core Function: Real-time clock (RTC) and calendar
• Interface: 2-line bidirectional I2C (Fast-mode Plus, 1 MHz)
• Time Resolution: Seconds to years
• Operating Voltage: 1.0V to 5.5V
• Low Backup Current: Typically 150 nA (at VDD=3.0V, 25°C)
• Key Features: Battery backup switch-over, programmable timer/alarm, oscillator stop detection, frequency offset adjustment
• Package: SOIC-8