PCF2123 Datasheet, PDF(1/54 Page) NXP Semiconductors

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PCF2123 Datasheet, PDF (1/54 Pages) NXP Semiconductors – SPI Real time clock/calendar

PCF2123

SPI Real time clock/calendar

Rev. 01 â 19 November 2008

Product data sheet

1. 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 ï¬ne tuning of the clock.

2. Features

I Real time clock provides year, month, day, weekday, hours, minutes and seconds

based on a 32.768 kHz quartz crystal

I Low backup current while running: typical 100 nA at VDD = 2.0 V and Tamb = 25 Â°C

I Resolution: seconds to years

I Watchdog functionality

I Freely programmable timer and alarm with interrupt capability

I Clock operating voltage: 1.1 V to 5.5 V

I 3 line SPI-bus with separate combinable data input and output

I Serial interface at VDD = 1.6 V to 5.5 V

I 1 second or 1 minute interrupt output

I Integrated oscillator load capacitors for CL = 7 pF

I Internal power-on reset

I Open-drain interrupt and clock output pins

I Programmable offset register for frequency adjustment

3. Applications

I Time keeping application

I Battery powered devices

I Metering

I High duration timers

I Daily alarms

I Low standby power applications

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