NXP ultra-low-power

RTC/calendars PCF8523

& PCF2123

Designed to perform critical time-keeping functions in a range of applications, these small, highly

efficient RTC/calendars fit nearly anywhere and cut power demands by as much as 60 percent.

Key features

} 32.768 kHz quartz crystal

} Resolution: seconds to years

} Freely programmable timer and alarm function with interrupt

} Low backup current: 100 nA typ at V

and Tamb = 25 °C

} Internal Power-On Reset

} Open drain interrupt and clock output pins

} Programmable offset register for frequency adjustment

} Watchdog timer

} Clock operating voltage: 1.2 V to 5.5 V

} Battery backup input pin and switch-over circuitry

} Integrated oscillator load capacitors for C

} Second countdown timer with interrupt output

Ultra-low-power SPI RTC/calendar PCF2123

} Clock operating voltage: 1.1 to 5.5 V

} 3-line SPI with separate, combinable data I/O

} Serial interface (at V

} Free programmable timer and alarm with interrupt capability

} Integrated oscillator load capacitors for C

Key applications

} Time-keeping functions

} Battery-powered devices

} Metering

} High-duration timers

} Daily alarms

} Systems with low standby power

The NXP PCF8523 and PCF2123 are CMOS devices that

combine a real-time clock (RTC) and a calendar. Optimized for

low power consumption, they operate at a current of less than

100 nA with a 2.0 V power supply, and consume less than 0.2μW

PCF2123 is equipped with an SPI serial interface.

Both devices are cased in tiny leadless packages that save

space in compact designs. This makes them well suited for

handheld and battery-operated applications, including blood-

pressure monitors and other home-use medical devices, pocket

calculators, portable phones, and PDAs. They are also an

excellent choice for white goods, such as washing machines,

metering units, and other industrial systems. Both devices can

be powered by a very small battery cell or a super-cap.

Save power with small,

ultra-efficient RTCs