PCF2123BS/1,518

The PCF2123 is a CMOS Real-Time Clock (RTC) and calendar optimized for low power applications. Data is transferred serially via a Serial Peripheral Interface (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.

• 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 ?
• 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, but combinable data input and output
• Serial interface at V_DD = 1.8 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 (POR)
• Open-drain interrupt and clock output pins
• Programmable offset register for frequency adjustment