Serial real-time clock (RTC) with 44 bytes NVRAM and reset

Download datasheet

Order a free sample and buy from our distributors

Sample & Buy
Overview
Tools & Software
Resources
Solutions
Quality & Reliability
Sales Briefcase
eDesignSuite
Get Started
Sample & Buy
Partner products
  • The M41T94 is a serial real-time clock with 44 bytes of NVRAM and a RESET output. A built-in 32,768 Hz oscillator (external crystal controlled) and 8 bytes of the SRAM (see Table 4 on page 18) are used for the clock/calendar function and are configured in binary coded decimal (BCD) format.

    An additional 12 bytes of RAM provide status/control of alarm, watchdog and square wave functions. Addresses and data are transferred serially via a serial SPI interface. The built-in address register is incremented automatically after each WRITE or READ data byte. The M41T94 has a built-in power sense circuit which detects power failures and automatically switches to the battery supply when a power failure occurs. The energy needed to sustain the SRAM and clock operations can be supplied by a small lithium button-cell supply when a power failure occurs. Functions available to the user include a non-volatile, time-of-day clock/calendar, alarm interrupts, watchdog timer and programmable square wave output. Other features include a power-on reset as well as two additional debounced inputs (RSTIN1and RSTIN2) which can also generate an output reset (RST). 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 - valid until year 2100), 30 and 31 day months are made automatically. The ninth clock address location controls user access to the clock information and also stores the clock software calibration setting.
    The M41T94 is supplied in either a 16-lead plastic SOIC (requiring user supplied crystal and battery) or a 28-lead SOIC SNAPHAT®package (which integrates both crystal and battery in a single SNAPHAT top). The 28-pin, 330 mil SOIC provides sockets with gold plated contacts at both ends for direct connection to a separate SNAPHAT housing containing the battery and crystal. The unique design allows the SNAPHAT battery/crystal package to be mounted on top of the SOIC package after the completion of the surface mount process.
    Insertion of the SNAPHAT housing after reflow prevents potential battery and crystal damage due to the high temperatures required for device surface-mounting. The SNAPHAT housing is also keyed to prevent reverse insertion.
    The SOIC and battery/crystal packages are shipped separately in plastic anti-static tubes or in tape & reel form. For the 28-lead SOIC, the battery/crystal package (e.g., SNAPHAT) part number is “M4TXX-BR12SH”.

    Key Features

    • Counters for tenths/hundredths of seconds, seconds, minutes, hours, day, date, month, year, and century
    • 32 KHz crystal oscillator integrating load capacitance (12.5 pF) providing exceptional oscillator stability and high crystal series resistance operation
    • Serial peripheral interface (2 MHz SPI)
    • Ultralow battery supply current of 500 nA (max)
    • 2.7 to 5.5 V operating voltage
    • 2.5 to 5.5 V oscillator operating voltage
    • Battery low flag
    • Automatic switchover and deselect circuitry
    • 44 bytes of general purpose RAM
    • Programmable alarm and interrupt function (valid even during battery backup mode)
    • Accurate programmable watchdog timer (from 62.5 ms to 128 s)
    • Microprocessor power-on reset
    • Choice of power-fail deselect voltages (VCC= 2.7 to 5.5 V):
      • THS = VSS; 2.55 V ≤ VPFD≤ 2.70 V
      • THS = VCC; 4.20 V ≤ VPFD≤ 4.50 V
    • Packaging includes a 28-lead SOIC and SNAPHAT®top (to be ordered separately) or 16-lead SOIC
    • 28-lead SOIC package provides direct connection for a SNAPHAT®top which contains the battery and crystal
    • RoHS compliant
      • Lead-free second level interconnect

Circuit Diagram

Download Download

Sample & Buy

Part Number
Package
Packing Type
Temperature (°C) Marketing Status
Budgetary Price (US$)*
Quantity
NVRAM size (B)
More info
Order from Distributors
Order from ST
min
max
M41T94MH6F SO-28 Tape And Reel -40 85
Active
2.823 10000 44
MORE INFO

ECCN (US):

EAR99

Country of Origin:

MALAYSIA

Check Availability

Distributor availability ofM41T94MH6F

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 2952 1 Order Now
RS COMPONENTS EUROPE 1854 1 Order Now
FUTURE WORLDWIDE 2808 936 Order Now
ARROW EUROPE 736 0 Order Now
ARROW AMERICA 3 1 Order Now
MOUSER WORLDWIDE 2373 1 Order Now

Distributor reported inventory date: 2019-11-27

Distributor Name

DIGIKEY

Stock

2952

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

1854

Min.Order

1

Region

EUROPE Order Now

FUTURE

Stock

2808

Min.Order

936

Region

WORLDWIDE Order Now

ARROW

Stock

736

Min.Order

0

Region

EUROPE Order Now

ARROW

Stock

3

Min.Order

1

Region

AMERICA Order Now

MOUSER

Stock

2373

Min.Order

1

Region

WORLDWIDE Order Now

Distributor reported inventory date: 2019-11-27

Get sample
M41T94MQ6F SO-16 Tape And Reel -40 85
Active
1.705 10000 44
MORE INFO

ECCN (US):

EAR99

Country of Origin:

MOROCCO

Check Availability

Distributor availability ofM41T94MQ6F

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 5503 1 Order Now
RS COMPONENTS EUROPE 4835 1 Order Now
AVNET AMERICA 18651 0 Order Now
FUTURE WORLDWIDE 2500 2500 Order Now
ARROW EUROPE 2503 0 Order Now
Newark Element14 AMERICA 217 0 Order Now
MOUSER WORLDWIDE 3489 1 Order Now
Farnell Element14 EUROPE 1148 1 Order Now
RUTRONIK EUROPE 2500 2500 Order Now

Distributor reported inventory date: 2019-11-27

Distributor Name

DIGIKEY

Stock

5503

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

4835

Min.Order

1

Region

EUROPE Order Now

AVNET

Stock

18651

Min.Order

0

Region

AMERICA Order Now

FUTURE

Stock

2500

Min.Order

2500

Region

WORLDWIDE Order Now

ARROW

Stock

2503

Min.Order

0

Region

EUROPE Order Now

Newark Element14

Stock

217

Min.Order

0

Region

AMERICA Order Now

MOUSER

Stock

3489

Min.Order

1

Region

WORLDWIDE Order Now

Farnell Element14

Stock

1148

Min.Order

1

Region

EUROPE Order Now

RUTRONIK

Stock

2500

Min.Order

2500

Region

EUROPE Order Now

Distributor reported inventory date: 2019-11-27

Get sample

M41T94MH6F

Package

SO-28

Packing Type

Tape And Reel

Unit Price (US$)

2.823*

Distributor availability ofM41T94MH6F

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 2952 1 Order Now
RS COMPONENTS EUROPE 1854 1 Order Now
FUTURE WORLDWIDE 2808 936 Order Now
ARROW EUROPE 736 0 Order Now
ARROW AMERICA 3 1 Order Now
MOUSER WORLDWIDE 2373 1 Order Now

Distributor reported inventory date: 2019-11-27

Distributor Name

DIGIKEY

Stock

2952

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

1854

Min.Order

1

Region

EUROPE Order Now

FUTURE

Stock

2808

Min.Order

936

Region

WORLDWIDE Order Now

ARROW

Stock

736

Min.Order

0

Region

EUROPE Order Now

ARROW

Stock

3

Min.Order

1

Region

AMERICA Order Now

MOUSER

Stock

2373

Min.Order

1

Region

WORLDWIDE Order Now

Distributor reported inventory date: 2019-11-27

Operating Temperature (°C)

(min)

-40

(max)

85

Marketing Status

Active

Unit Price (US$)

2.823

Quantity

10000

NVRAM size (B)

44

ECCN (US)

EAR99

Country of Origin

MALAYSIA

M41T94MQ6F

Package

SO-16

Packing Type

Tape And Reel

Unit Price (US$)

1.705*

Distributor availability ofM41T94MQ6F

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 5503 1 Order Now
RS COMPONENTS EUROPE 4835 1 Order Now
AVNET AMERICA 18651 0 Order Now
FUTURE WORLDWIDE 2500 2500 Order Now
ARROW EUROPE 2503 0 Order Now
Newark Element14 AMERICA 217 0 Order Now
MOUSER WORLDWIDE 3489 1 Order Now
Farnell Element14 EUROPE 1148 1 Order Now
RUTRONIK EUROPE 2500 2500 Order Now

Distributor reported inventory date: 2019-11-27

Distributor Name

DIGIKEY

Stock

5503

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

4835

Min.Order

1

Region

EUROPE Order Now

AVNET

Stock

18651

Min.Order

0

Region

AMERICA Order Now

FUTURE

Stock

2500

Min.Order

2500

Region

WORLDWIDE Order Now

ARROW

Stock

2503

Min.Order

0

Region

EUROPE Order Now

Newark Element14

Stock

217

Min.Order

0

Region

AMERICA Order Now

MOUSER

Stock

3489

Min.Order

1

Region

WORLDWIDE Order Now

Farnell Element14

Stock

1148

Min.Order

1

Region

EUROPE Order Now

RUTRONIK

Stock

2500

Min.Order

2500

Region

EUROPE Order Now

Distributor reported inventory date: 2019-11-27

Operating Temperature (°C)

(min)

-40

(max)

85

Marketing Status

Active

Unit Price (US$)

1.705

Quantity

10000

NVRAM size (B)

44

ECCN (US)

EAR99

Country of Origin

MOROCCO

(*) 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

Recommended for you

Embedded Software

00 Files selected for download

Technical Documentation

    • Description Version Size Action
      DS2166
      Serial real-time clock with 44 bytes NVRAM and reset
      7.0
      555.04 KB
      PDF
      DS2166

      Serial real-time clock with 44 bytes NVRAM and reset

    • Description Version Size Action
      AN3060
      Applications guide for serial real-time clocks (RTCs)
      3.0
      878.56 KB
      PDF
      AN1011
      Battery technology used in NVRAM and real-time clock (RTC) products from ST
      4.0
      248.17 KB
      PDF
      AN934
      How to use the digital calibration feature in TIMEKEEPER® and serial real-time clock (RTC) products
      4.1
      123.42 KB
      PDF
      AN1216
      Implementing a periodic alarm with TIMEKEEPER® and serial real-time clocks (RTCs)
      2.0
      192.89 KB
      PDF
      AN4641
      Integrating TIMEKEEPER® and real-time clock supervisor functions
      1.0
      479.28 KB
      PDF
      AN923
      Managing century information using serial real-time clocks and TIMEKEEPER® NVRAMs
      4.0
      142.23 KB
      PDF
      AN1572
      Power-down time-stamp function in serial real-time clocks (RTCs)
      2.0
      171.31 KB
      PDF
      AN1336
      Power-fail comparator for NVRAM supervisory devices
      2.0
      127.81 KB
      PDF
      AN1012
      Predicting the battery life and data retention period of NVRAMs and serial RTCs
      4.1
      439.45 KB
      PDF
      AN922
      Using a Super Cap to back up the M41T56, M41T00, M41T11, M41T81, M41T94, and M41ST84W (16-pin)
      2.1
      84.5 KB
      PDF
      AN3060

      Applications guide for serial real-time clocks (RTCs)

      AN1011

      Battery technology used in NVRAM and real-time clock (RTC) products from ST

      AN934

      How to use the digital calibration feature in TIMEKEEPER® and serial real-time clock (RTC) products

      AN1216

      Implementing a periodic alarm with TIMEKEEPER® and serial real-time clocks (RTCs)

      AN4641

      Integrating TIMEKEEPER® and real-time clock supervisor functions

      AN923

      Managing century information using serial real-time clocks and TIMEKEEPER® NVRAMs

      AN1572

      Power-down time-stamp function in serial real-time clocks (RTCs)

      AN1336

      Power-fail comparator for NVRAM supervisory devices

      AN1012

      Predicting the battery life and data retention period of NVRAMs and serial RTCs

      AN922

      Using a Super Cap to back up the M41T56, M41T00, M41T11, M41T81, M41T94, and M41ST84W (16-pin)

    • Description Version Size Action
      UM0402
      Single-phase multi tariff energy meter
      1.3
      587.7 KB
      PDF
      UM0402

      Single-phase multi tariff energy meter

HW Model, CAD Libraries & SVD

    • Description Version Size Action
      Ibis model 1.0
      22.99 KB
      ZIP

      Ibis model

Publications and Collaterals

    • Description Version Size Action
      Serial real-time clock ICs 1.0
      827.11 KB
      PDF

      Serial real-time clock ICs

Quality & Reliability

    • Description Version Size Action
      Products Underwriter Laboratories (UL) Information 2.1
      543.21 KB
      PDF

      Products Underwriter Laboratories (UL) Information

Part Number Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
M41T94MH6F
Active
SO-28 Industrial Ecopack1
M41T94MQ6F
Active
SO-16 Industrial Ecopack1 (*)

M41T94MH6F

Package:

SO-28

Material Declaration**:

PDF XML

Marketing Status

Active

Package

SO-28

Grade

Industrial

RoHS Compliance Grade

Ecopack1

M41T94MQ6F

Package:

SO-16

Material Declaration**:

PDF XML

Marketing Status

Active

Package

SO-16

Grade

Industrial

RoHS Compliance Grade

Ecopack1 (*)

(**) 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.

Support & Feedback