M41T64

Part: M41T62, M41T64, M41T65 — STMicroelectronics

Type: Low-power serial real-time clock (RTC) with alarm

Description: The M41T6x is a low-power serial real-time clock (RTC) with a built-in 32.768 kHz oscillator, I2C interface, and alarm functions, offering timekeeping down to 1.0 V and operating from -40 to +85 °C.

Operating Conditions:

• Supply voltage: 1.3 V to 4.4 V (I2C bus operating voltage)
• Operating temperature: -40 to +85 °C
• Timekeeping voltage: down to 1.0 V

Absolute Maximum Ratings:

• Max supply voltage: 4.4 V

Key Specs:

• Timekeeping current: 350 nA at 3 V
• Operating current: 35 μA (at 400 kHz I2C speed)
• I2C serial interface speed: 400 kHz
• Timekeeping accuracy: ±2 parts per million (±5 seconds per month) with software calibration
• Watchdog timeout: -62.5 ms to 31 min
• Oscillator: Built-in 32.768 kHz oscillator with integrated crystal load capacitors

Features:

• Memory mapped registers for seconds, minutes, hours, day, date, month, year, and century
• Tenths/hundredths of seconds register
• Automatic leap year compensation
• Oscillator stop detection
• Programmable alarm with interrupt function (M41T62/65)
• Programmable 1 Hz to 32 KHz square wave output (M41T62/64)
• 32 KHz square wave output on at powerup (M41T62/64)
• Accurate programmable watchdog
• Software clock calibration

Applications:

Package:

• 16-lead QFN (3 x 3 mm)
• 8-pin ceramic leadless chip carrier (LCC) (1.5 x 3.2 mm) with embedded 32 KHz crystal (M41T62)

• Serial real-time clock (RTC) with alarm functions
• -400 kHz I 2 C 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 I 2 C bus operating voltage
• -4.4 V max VCC suitable for lithium-ion battery operation
• Low operating current of 35 μA (at 400 kHz I 2 C speed)

• Contents Contents Contents Contents
• 1 Description.......................................................................................6
• 2 Operation .......................................................................................11
• 2.1 2-wire bus characteristics................................................................11
• 2.1.1 Bus not busy..................................................................................... 11
• 2.1.2 Start data transfer............................................................................. 11
• 2.1.3 Stop data transfer............................................................................. 11
• 2.1.4 Data valid.......................................................................................... 12
• 2.1.5 Acknowledge .................................................................................... 12
• 2.2 READ mode....................................................................................13
• 2.3 WRITE mode...................................................................................15
• 3 Clock operation .............................................................................16
• 3.1 RTC registers..................................................................................17
• 3.2 Calibrating the clock........................................................................22
• 3.3 Setting alarm clock registers ...........................................................24
• 3.4 Watchdog timer...............................................................................25
• 3.5 Watchdog output ( 𝐖𝐖𝐖𝐖𝐖𝐖 - M41T65 only) .........................................25
• 3.6 Square wave output (M41T62/64)...................................................26
• 3.7 Full-time 32 KHz square wave output (M41T64).............................26
• 3.8 Century bits.....................................................................................27
• 3.9 Leap year........................................................................................27
• 3.10 Output driver pin (M41T62/65)........................................................28
• 3.11 Oscillator stop detection..................................................................28
• 3.12 Initial power-on defaults ..................................................................28
• 4 Maximum ratings...........................................................................29
• 5 DC and AC parameters .................................................................30
• 6 Package information .....................................................................34
• 6.1 QFN16 package information ...........................................................35
• 6.2 LCC8 package information..............................................................38
• 7 Packing information......................................................................40
• 7.1 QFN16 carrier tape .........................................................................40
• 7.2 LCC8 carrier tape............................................................................41
• 7.3 Reel information for QFN16 and LCC8...........................................42
• 2/45 DocID10397 Rev 21 DocID10397 Rev 21

Revision history ............................................................................ 44

Stressing the device above the rating listed in the absolute maximum ratings table may cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other conditions above those indicated in the operating sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

Table 10: Absolute maximum ratings

(1) Test conforms to JEDEC standard.

(2) Data based on characterization results, not tested in production.

(3) Reflow at peak temperature of 260 °C. The time above 255 °C must not exceed 30 seconds.

In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK ® packages, depending on their level of environmental compliance. ECOPACK ® specifications, grade definitions and product status are available at: www.st.com . ECOPACK ® is an ST trademark.