PCF8523: 100 nA Real-time clock/calendar with battery backup

Overview

The PCF8523 is a CMOS 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.

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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 V_DD = 3.0 V and T_amb = 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 C_L = 7 pF or C_L = 12.5 pF
Internal Power-On Reset (POR)
Open-drain interrupt or clock output pins
Programmable offset register for frequency adjustment

Target Applications

Time keeping application
Battery powered devices
Metering

MoreLess

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 V_DD = 3.0 V and T_amb = 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 C_L = 7 pF or C_L = 12.5 pF
Internal Power-On Reset (POR)
Open-drain interrupt or clock output pins
Programmable offset register for frequency adjustment

Target Applications

Time keeping application
Battery powered devices
Metering

Data Sheets

Application Notes

Sample

Development Boards

OM13511:I²C-bus RTC PCF8523 demoboard

Development Boards

OM13511:I²C-bus RTC PCF8523 demoboard