M41T62, M41T64, M41T65 Datasheet Low-power serial real-time clocks (RTCs) with alarm 3mm Features 3mm Serial real-time clock (RTC) with alarm functions 400 kHz IC serial interface QFN16 3 x 3 mm Memory mapped registers for seconds, minutes, hours, day, date, month, 1.5 mm 3.2 mm year, and century Tenths/hundredths of second register Embedded crystal LCC8 1.5 x 3.2 mm 350 nA timekeeping current at 3 V No external crystal required Time keeping down to 1.0 V 1.3 V to 4.4 V IC bus operating voltage 4.4 V max. V suitable for lithium-ion battery operation CC Low operating current of 35 A (at 400 kHz IC 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) Maturity status link Automatic leap year compensation M41T62 40 to + 85 C operation M41T64 Two package options Very small 3 x 3 mm, lead-free and halogen-free (ECOPACK2) 16-lead M41T65 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) DS3840 - Rev 24 - September 2019 www.st.com For further information contact your local STMicroelectronics sales office.M41T62, M41T64, M41T65 Description 1 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 IC interface. The built-in address register is incremented automatically 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 32 kHz 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, second and tenths/hundredths of a second in 24-hour BCD format. Corrections for 28-, 29- (leap year), 30- and 31-day months 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-supplied 32 kHz crystal, and an ultra-small 1.5 x 3.2 mm LCC with embedded crystal - no external crystal is required. Table 1. Device summary F 32K OSC fail SQW Device Basic RTC Alarms Watchdog timer Calibration IRQ output WDO output detect output output M41T62 M41T64 M41T65 Figure 1. M41T62 logic diagram V CC (3) XI (3) (1) XO IRQ/OUT M41T62 (2) SCL SQW SDA V SS 1. Open drain. 2. Defaults to 32 kHz on power-up. 3. Not bonded on LCC package. DS3840 - Rev 24 page 2/42