M41T66
Serial real-time clock (RTC) with alarm-
Active
The M41T66 is a low-power serial real-time clock (RTC) with a built-in 32.768 kHz oscillator (external crystal controlled). 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, square wave, 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, programmable square wave output, and watchdog output. 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 M41T66 is supplied in a 16-pin QFN.
Download
Datasheet
Key Features
- Counters for tenths/hundredths of seconds, seconds, minutes, hours, day, date, month, year, and century
- 32 KHz crystal oscillator integrating load capacitance and high crystal series resistance operation
- Oscillator stop detection monitors clock operation
- Serial interface supports I2C bus (400 kHz)
- 525 nA timekeeping current at 3 V
- Low operating current of 35 μA (at 400 kHz)
- Timekeeping down to 1.0 V
- 1.3 V to 4.4 V I2C bus operating voltage
Allows use in lithium ion rechargeable applications - 32 KHz square wave on power-up to drive a microcontroller in low-power mode
- Programmable (1 Hz to 32 KHz) square wave
- Programmable alarm with interrupt function
- Accurate programmable watchdog (from 62.5 ms to 31 min)
- Software clock calibration to compensate deviation of crystal due to temperature
- Automatic leap year compensation
- Operating temperature of –40 to 85 °C
- Lead-free 16-pin QFN package
Circuit Diagram
Design Resources
TopTechnical Documentation
Product Specifications
| Description | Version | Size |
|---|---|---|
DS5956: Serial real-time clock with alarms
|
2.0 | 412 KB |
Application Notes
| Description | Version | Size |
|---|---|---|
|
AN1011: Battery technology used in NVRAM and real-time clock (RTC) products from ST
|
4.0 | 248 KB |
|
AN1572: Power-down time-stamp function in serial real-time clocks (RTCs)
|
2.0 | 171 KB |
|
AN1879: How to use M41ST87 tamper detect and RAM clear
|
4.2 | 70 KB |
|
AN3060: Applications guide for serial real-time clocks (RTCs)
|
2.0 | 355 KB |
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AN934: How to use the digital calibration feature in TIMEKEEPER® and serial real-time clock (RTC) products
|
4.1 | 123 KB |
Technical Notes & Articles
| Description | Version | Size |
|---|---|---|
|
TA0344: Highly accurate, automatic temperature-compensated real-time clock (RTC) solution
|
1.0 | 251 KB |
Related Tools and Software
Related Tools and Software
| Part Number | Description |
|---|---|
| STSW-SRTC001 | I2C code for Serial RTC |
| STSW-SRTC002 | SPI code -Serial RTC |
Publications and Collaterals
Brochure
| Description | Version | Size |
|---|---|---|
|
Serial real-time clock (RTC) ICs
|
1.0.0 | 2,329 KB |
Sample & Buy
Top| Part Number | Marketing Status | Package | Packing Type | Operating Temperature (min) | Operating Temperature (max) | NVRAM size | Automotive Grade | Order From ST | Unit Price (US$)* @ | Distributor Availability | RoHS Compliance Grade | Download Material Declaration** |
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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M41T66Q6F | Active | VFQFPN 16 3x3x0.9 | Tape And Reel | -40 | 85 | _ |
| Ecopack2 | PDF XML | ||||||||||||||||||
(*) 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 (**) 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. |
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