Description
The M41T6x is a low-power serial real-time clock (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. Further eight registers provide status/control of alarm, 32 kHz output, calibration, and watchdog functions. Addresses and data are transferred serially via a two-line, bidirectional I²C interface. The built-in address register is incremented automatically after each WRITE or READ data byte.

FEATUREs
• Serial real-time clock (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 second register
• 350 nA timekeeping current at 3 V
• Time keeping 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 I²C speed)
• 32 kHz square wave output is on at power-up. Suitable for driving a
   microcontroller in low-power mode. Can be disabled. (M41T62/64)
• Programmable 1 Hz to 32 kHz square wave output (M41T62/64)
• 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 minutes timeout
• Software clock calibration. Timekeeping can be adjusted within ± 2 parts per
   million (± 5 seconds per month)
• Automatic leap year compensation
• – 40 to + 85 °C operation
• Two package options
   – Very small 3 x 3 mm, lead-free and halogen-free (ECOPACK2) 16-lead
      QFN
   – Ultra small 1.5 x 3.2 mm, lead-free and halogen-free (ECOPACK2) 8-pin
      ceramic leadless chip carrier with embedded 32 kHz crystal - no external
      oscillator components required (M41T62)