NXP ultra-low-power RTC/calendars PCF8523 & PCF2123 Save power with small, ultra-efficient RTCs 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 VDD = 2.0 V and Tamb = 25 °C } Internal Power-On Reset } Open drain interrupt and clock output pins } Programmable offset register for frequency adjustment } Watchdog timer Ultra-low-power I2C RTC/calendar PCF8523 } Clock operating voltage: 1.2 V to 5.5 V } 2 line bi-directional 1 MHz Fast-mode Plus I2C interface } Battery backup input pin and switch-over circuitry } Integrated oscillator load capacitors for CL = 7 and 12.5 pF }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 VDD = 1.6 to 5.5 V) } Free programmable timer and alarm with interrupt capability } Integrated oscillator load capacitors for CL = 7 pF 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 0.2 μW of power. The PCF8523 uses an I2C-bus serial interface while the 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 bloodpressure 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. The calendar functions track year, month, weekday, and day with built-in Leap Year correction. The programmable alarm and timer function gives the option of generating a wake-up signal on an interrupt pin. In the PCF2123, the Watchdog timer can be used to wake a microcontroller from hibernation mode or monitor microcontroller tasks independently. PCF8523 block diagram PCF2123 block diagram Selection guide Characteristics PCF8523 PCF2123 PCF85(1)63 PCA21125 PCA8565 Interface Temperature range Supply voltage V DD clock Supply voltage V DD interface Supply current at V DD = 2 V Electronic tuning I 2C -40º to +85 °C 1.2 to 5.5 V 1.6 to 5.5 V 100 nA yes SPI -40º to +85 ºC 1.1 V to 5.5 V 1.6 V to 5.5 V 100 nA yes I 2C -40 to +85 °C 1.0 to 5.5 V 1.8 to 5.5 V 270 nA no SPI -40 to +125 °C 1.3 to 5.5 V 1.6 to 5.5 V 640 nA no I2C -40 to +125 °C 1.0 to 5.5 V 1.8 to 5.5 V 600 nA no Ordering Information Type Package tape and reel Type Version PCF8523T/1 PCF8523TS/1 SO8, plastic small outline package; 8 leads; body width 3.9 mm TSSOP14, plastic thin shrink small outline package; 14 leads; body width 4.4 mm SOT96-1 SOT402-1 1 1 PCF8523TK/1 HVSON8, plastic thermal enhanced very thin small outline package; no leads; 8 terminals; 4 x 4 x 0.85 mm SOT909-1 1 PCF2123TS/1 TSSOP14, plastic thin shrink small outline package, 14 leads; body width 4.4 mm SOT402-1 1 PCF2123BS/1 HVQFN16, plastic thermal enhanced very thin quad flat package; no leads; 16 terminals; body 3 x 3 x 0.85 mm SOT758-1 1 PCF2123U/10AA/1 PCF2123U/12AA/1 PCF2123U/12HA/1 PCF8523U/12AA/1 Bare die, die thickness 200 µm Bare die with gold bumps, die thickness 200 µm Bare die with gold bumps, die thickness 150 µm Bare die with gold bumps, die thickness 200 µm - 1 1 1 1 www.nxp.com © 2011 NXP Semiconductors N.V. All rights reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. Date of release: March 2011 The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable Document order number : 9397 750 17076 and may be changed without notice. No liability will be accepted by the publisher for any consequence of its use. Publication Printed in the Netherlands thereof does not convey nor imply any license under patent- or other industrial or intellectual property rights.