PCF8523 Datasheet, PDF (1/66 Pages) NXP Semiconductors – Real-Time Clock (RTC) and calendar

PCF8523
Real-Time Clock (RTC) and calendar
Rev. 3 — 30 March 2011
Product data sheet
1. General description
The PCF8523 is a CMOS¹ Real-Time Clock (RTC) and calendar optimized for low power
consumption. Data is transferred serially via an I²C-bus with a maximum data rate of
1000 kbit/s. Alarm and timer functions are available with the possibility to generate a
wake-up signal on an interrupt pin. An offset register allows fine-tuning of the clock. The
PCF8523 has a backup battery switch-over circuit, which detects power failures and
automatically switches to the battery supply when a power failure occurs.
2. Features and benefits
 Provides year, month, day, weekday, hours, minutes, and seconds based on a
32.768 kHz quartz crystal
 Resolution: seconds to years
 Clock operating voltage: 1.0 V to 5.5 V
 Low backup current: typical 150 nA at V_DD = 3.0 V and T_amb = 25 C
 2 line bidirectional 1 MHz Fast-mode Plus (Fm+) I²C interface
 Battery backup input pin and switch-over circuit
 Freely programmable timer and alarm with interrupt capability
 Selectable integrated oscillator load capacitors for C_L = 7 pF or C_L = 12.5 pF
 Internal Power-On Reset (POR)
 Open-drain interrupt or clock output pins
 Programmable offset register for frequency adjustment
3. Applications
 Time keeping application
 Battery powered devices
 Metering
1. The definition of the abbreviations and acronyms used in this data sheet can be found in Section 19.