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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. An additional 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.
Functions available to the user include a time-of-day clock/calendar, alarm interrupts (M41T62/65), 32 kHz output (M41T62/64), programmable square wave output (M41T62/64), and 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.Key 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 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 VCCsuitable 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. Can adjust timekeeping to 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)
- Serial real-time clock (RTC) with alarm functions
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Sample & Buy
| Part Number | Package | Packing Type | Temperature (°C) | Marketing Status | NVRAM size (B) | ECCN (US) | Country of Origin | Budgetary Price (US$)*/Qty | Order from ST | Order from Distributors | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| min | max | ||||||||||
| M41T62LC6F | LCC8 3.2x1.5 mm | Tape And Reel | -40 | 85 | Active | - | EAR99 | TAIWAN | 2.3 / 1k | Get sample | Check Availability |
| M41T62Q6F | VFQFPN 16 3x3x0.9 | Tape And Reel | -40 | 85 | Active | - | EAR99 | MALAYSIA | 0.8 / 1k | Get sample | Check Availability |
(*) Suggested Resale Price per unit (USD) for BUDGETARY USE ONLY. For quotes, prices in local currency, please contact your local ST Sales Office or our Distributors
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Picture Part number Manufacturer Description 
STEVAL-FET001V1 ST M41T62LC6F adapter board for a standard DIL 24 socket Part NumberM41T62LC6F adapter board for a standard DIL 24 socket
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| Part Number | Marketing Status | Package | Grade | RoHS Compliance Grade | Material Declaration** |
|---|---|---|---|---|---|
| M41T62LC6F | Active | LCC8 3.2x1.5 mm | Industrial | Ecopack2 | |
| M41T62Q6F | Active | VFQFPN 16 3x3x0.9 | Industrial | Ecopack2 |
(**) The Material Declaration forms available on st.com may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.
