Description
The M41T6x serial access TIMEKEEPER® is a low power serial RTC with a built-in 32.768 kHz oscillator. Eight registers are used for the clock/calendar function and are configured in binary coded decimal (BCD) format. An additional 8 registers provide status/control of alarm, 32 KHz output, calibration, and watchdog functions. Addresses and data are transferred serially via a two line, bi-directional I2C interface. The built-in address register is incremented automatically after each WRITE or READ data byte.

Features
■ Serial RTC with alarm functions
   – 400 kHz I2C serial interface
   – Memory mapped registers for seconds,
      minutes, hours, day, date, month, year, and
      century
   – Tenths/hundredths of seconds register
■ 350 nA timekeeping current at 3 V
■ Timekeeping down to 1.0 V
■ 1.3 V to 4.4 V I2C bus operating voltage
   – 4.4 V max VCC suitable for lithium-ion
      battery operation
■ Low operating current of 35 µA (at 400 kHz)
■ 32 KHz square wave output is on at power-up.
   Suitable for driving a microcontroller in
   low-power mode. Can be disabled.
   (M41T62/63/64)
■ Programmable 1 Hz to 32 KHz square wave
   output (M41T62/63/64)
■ Programmable alarm with interrupt function
   (M41T62/65)
■ 32 KHz crystal oscillator integrates crystal load
   capacitors, works with high series resistance
   crystals
■ Oscillator stop detection monitors clock
   operation
■ Accurate programmable watchdog
   – 62.5 ms to 31 min timeout
■ Software clock calibration. Can adjust
   timekeeping to within ±2 parts per million (±5
   seconds per month)
■ Automatic leap year compensation
■ –40 to +85 °C operation
■ Very small 3 mm x 3 mm, Lead-free
   16-lead QFN