The PCF8523 is a CMOS1 Real-Time Clock (RTC) and calendar optimized for low power consumption. Data is transferred serially via the I2C-bus with a maximum data rate of 1000 kbit/s. Alarm and timer functions are available with the possibility to generate a wake-up signal on an interrupt pin. An offset register allows fine-tuning of the clock. The PCF8523 has a backup battery switch-over circuit, which detects power failures and automatically switches to the battery supply when a power failure occurs.

### TECHNICAL DETAILS / COMPONENTS

Features

• Provides year, month, day, weekday, hours, minutes, and seconds based on a 32.768 kHz quartz crystal
• Resolution: seconds to years
• Clock operating voltage: 1.0 V to 5.5 V
• Low backup current: typical 150 nA at VDD = 3.0 V and Tamb = 25 °C
• 2 line bidirectional 1 MHz Fast-mode Plus (Fm+) I2C interface, read D1h, write D0h
• Battery backup input pin and switch-over circuit
• Freely programmable timer and alarm with interrupt capability
• Selectable integrated oscillator load capacitors for CL= 7 pF or CL = 12.5 pF
• Internal Power-On Reset (POR)
• Open-drain interrupt or clock output pins
• Programmable offset register for frequency adjustment

### LEARN / TOPIC / BUILD INSTRUCTIONS

https://www.nxp.com/products/analog/interfaces/ic-bus/ic-real-time-clocks-rtc/real-time-clock-rtc-and-calendar:PCF8523

http://www.chayut.me/

By Chayut Orapinpatipat

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