PCF2123

General description

The PCF2123 is a CMOS real time clock and calendar optimized for low power applications. Data is transferred serially via a Serial Peripheral Interface bus (SPI-bus) with a maximum data rate of 6.25 Mbit/s. An alarm and timer function is also available providing the possibility to generate a wake-up signal on an interrupt pin. An offset register allows fine tuning of the clock.

Features

• Real time clock provides year, month, day, weekday, hours, minutes and seconds based on a 32.768 kHz quartz crystal
• Low backup current while running: typical 100 nA at V_DD = 2.0 V and T_amb = 25 Cel
• Resolution: seconds to years
• Watchdog functionality
• Freely programmable timer and alarm with interrupt capability
• Clock operating voltage: 1.1 V to 5.5 V
• 3 line SPI-bus with separate combinable data input and output
• Serial interface at V_DD = 1.6 V to 5.5 V
• 1 second or 1 minute interrupt output
• Integrated oscillator load capacitors for C_L = 7 pF
• Internal power-on reset
• Open-drain interrupt and clock output pins
• Programmable offset register for frequency adjustment

Products/packages

Pricing/ordering/availability

Applications

• Time keeping application
• Battery powered devices
• Metering
• High duration timers
• Daily alarms
• Low standby power applications

Block diagrams/pinning

Design support

Support Documents

UM10301_1; User Manual for NXP Real Time Clocks PCF85x3, PCA8565 and PCF2123, PCA2125 (2008-12-30)

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