Description:

The M41T6x is a low-power serial real-time clock (RTC) with a built-in 32.768 kHz oscillator. Eight registers areused for the clock/calendar function and are configured in binary-coded decimal (BCD) format. Further eightregisters provide status/control of alarm, 32 kHz output, calibration, and watchdog functions. Addresses and dataare transferred serially via a two-line, bidirectional I²C interface. The built-in address register is incrementedautomatically after each WRITE or READ data byte.Functions available to the user include a time-of-day clock/calendar, an alarm interrupt (M41T62/M41T65), a 32kHz output (M41T62/M41T64), a programmable square wave output (M41T62/M41T64), and a watchdog output(M41T65). The eight clock address locations contain the century, year, month, date, day, hour, minute, secondand tenths/hundredths of a second in 24-hour BCD format. Corrections for 28-, 29- (leap year), 30- and 31-daymonths are made automatically.The M41T6x is supplied in two very small packages: a tiny, 3 x 3 mm 16-pin QFN which requires a user-supplied32 kHz crystal, and an ultra-small 1.5 x 3.2 mm LCC with embedded crystal - no external crystal is required.

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 amicrocontroller 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 highseries 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 permillion (± 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-leadQFN

– Ultra small 1.5 x 3.2 mm, lead-free and halogen-free (ECOPACK2) 8-pinceramic leadless chip carrier with embedded 32 kHz crystal - no externaloscillator components required (M41T62)