M41T66：Serial real-time clock (RTC) with alarm
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.
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 I2 C 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 I2
C 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
Product Specifications
| Description | Version | Size |
|---|---|---|
| DS5956: Serial real-time clock with alarms | 2.0 | 411 KB |
Application Notes
Brochures
| Description | Version | Size |
|---|---|---|
| Serial real-time clock ICs | 1.0 | 827 KB |
Clocks and Timers Software
| Part Number | Manufacturer | Description |
|---|---|---|
| STSW-SRTC001 | ST | I2C code for Serial RTC |
| STSW-SRTC002 | ST | SPI code -Serial RTC |
Sample & Buy
| Part Number | Package | Packing Type | Operating Temperature (°C) (min) | Operating Temperature (°C) (max) | Unit Price (US$) * | Quantity | NVRAM size (B) | ECCN (EU) | ECCN (US) | Country of Origin |
|---|---|---|---|---|---|---|---|---|---|---|
| M41T66Q6F | VFQFPN 16 3x3x0.9 | Tape And Reel | -40 | 85 | 0.823 | 1000 | - | NEC | EAR99 | MALAYSIA |
Quality & Reliability
| Part Number | Package | Grade | RoHS Compliance Grade | Material Declaration** |
|---|---|---|---|---|
| M41T66Q6F | VFQFPN 16 3x3x0.9 | Industrial | Ecopack2 | md_of-wspc-vfqfpn-wspc-3x3x0.9-wspc-1.7-wspc-16l_edzq2lla266-wspc-(m41t66q6f).pdf md_of-wspc-vfqfpn-wspc-3x3x0.xml |
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