NXP Semiconductors PCF85053A RTC

PCF85053A is a CMOS real-time clock (RTC) and calendar, optimized for low power consumption and automatic switching to battery on primary power loss. Featuring clock output, alert interrupt output and 128-byte battery backed-up SRAM, the PCF85053A includes two I2C buses. The primary I2C bus has the read / write capability on RTC and SRAM registers; the second I2C bus also can read / write most registers with the control bits set by primary I2C controller.

PCF85053A offers clock output calibration-related registers such as crystal capacitive load (CL) configuration and offset register setting.

Key features

• Real-time clock and calendar
• Provides year, month, day, weekday, hours, min and sec based on a 32.768 kHz quartz
• Two independent I2C interfaces
• Active low alert interrupt output

Additional features

• Operating voltage
  • Supply voltage: 1.7 V to 3.6 V
  • Battery supply voltage: 1.55 V to 3.6 V
     
• Communication interface
  • Two independent I2C interfaces:Primary I2C bus: read / write capability on RTC and SRAM registers
  • Second I2C bus: read / write capability on RTC and SRAM registers enabled by primary I2C
  • I2C device addresses:RTC: 1101 111
  • SRAM: 1010 111
  • I2C clock features:Max CLK frequency 400 kHz
  • Max CLK timeout 35 ms
  • I2C bus not active when switch over to battery
     
• Real time clock features
  • Real-time clock and calendar
  • Provides year, month, day, weekday, hours, minutes and seconds based on a 32.768 kHz quartz crystal
  • Support both binary mode and BCD mode
  • Support 24-hour and 12-hour mode
  • Support daylight saving mode
  • Oscillator fail flag
  • RTC clear flag
  • RTC fail flag
  • Alarm flag
     
• Extra features
  • Active low alert interrupt output
  • Register definition aligned to MC146818B (0 to 9 h)
  • Configurable oscillator circuit for a wide variety of quartzes: CL = 6 pF, CL = 7 pF, and CL = 12.5 pF
  • Operating temperature range -40 °C to 85 °C
  • Battery-backed 128 byte SRAM
  • SRAM clear to ‘0’ by RTC_CLR# pin
  • Frequency adjustment via programmable offset register

Applications

• Interface ICs for servers used in data centers
• Air Conditioning (AC)
• Heat metering
• Industrial HMI
• Industrial HMI
• Motion control and robotics
• Programmable Logic Controller (PLC) and Remote I/O
• Open and closed loop payments
• POS Terminal