M41ST87W

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5.0 V, 3.3/3.0 V secure real-time clock , NVRAM supervisor with tamper detection and 128 bytes of clearable NVRAM

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  • The M41ST87Y/W secure serial RTC and NVRAM supervisor is a low power 1280-bit, static CMOS SRAM organized as 160 bytes by 8 bits. A built-in 32.768 kHz oscillator (internal crystal-controlled) and 8 bytes of the SRAM are used for the clock/calendar function and are configured in binary coded decimal (BCD) format.

    An additional 11 bytes of RAM provide calibration, status/control of alarm, watchdog, tamper, and square wave functions. 8 bytes of ROM and finally 128 bytes of user RAM are also provided. 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. The M41ST87Y/W 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, tamper detection, 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), 30 and 31 day months are made automatically.

    Key Features

    • 5.0, 3.3, or 3.0 V operation
    • 400 kHz I2C bus
    • NVRAM supervisor to non-volatize external LPSRAM
    • 2.5 to 5.5 V oscillator operating voltage
    • Automatic switchover and deselect circuitry
    • Choice of power-fail deselect voltages
      • M41ST87Y: (not recommended for new design, contact ST sales office for availability) THS = 1: VPFD≈ 4.63 V; VCC= 4.75 to 5.5 V THS = 0: VPFD≈ 4.37 V; VCC= 4.5 to 5.5 V
      • M41ST87W: THS = 1: VPFD≈ 2.9 V; VCC= 3.0 to 3.6 V THS = 0: VPFD≈ 2.63 V; VCC= 2.7 to 3.6 V
    • Two independent power-fail comparators (1.25 V reference)
    • Counters for tenths/hundredths of seconds, seconds, minutes, hours, day, date, month, year, and century
    • 128 bytes of clearable, general purpose NVRAM
    • Programmable alarm and interrupt function (valid even during battery backup mode)
    • Programmable watchdog timer
    • Unique electronic serial number (8-byte)
    • 32 kHz frequency output available upon power-on
    • Microprocessor power-on reset output
    • Battery low flag
    • Ultra-low battery supply current of 500 nA (typ)
    • Security features
      • Tamper indication circuits with timestamp and RAM clear
      • LPSRAM clear function (TPCLR)
      • Packaging includes a 28-lead, embedded crystal SOIC and a 20-lead SSOP
      • Oscillator stop detection

Circuit Diagram

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Technical Documentation

    • Description Version Size Action
      DS3301
      5.0 V and 3.3/3.0 V secure serial RTC and NVRAM supervisor with tamper detection and 128 bytes of clearable NVRAM
      11.0
      1.06 MB
      PDF
      DS3301

      5.0 V and 3.3/3.0 V secure serial RTC and NVRAM supervisor with tamper detection and 128 bytes of clearable NVRAM

    • 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
      AN1879
      How to use the M41ST87W tamper detect and RAM clear
      5.0
      107.23 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
      AN3060

      Applications guide for serial real-time clocks (RTCs)

      AN1011

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

      AN1879

      How to use the M41ST87W tamper detect and RAM clear

      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

HW Model, CAD Libraries & SVD

    • Description Version Size Action
      Ibis model 1.0
      14.7 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 and Reliability

Part Number Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
M41ST87WMX6TR
Active
SO28 WITH EMBEDDED CRYSTAL Industrial Ecopack1
M41ST87WSS6F
Active
SSOP 20 7.2x5.3 Industrial Ecopack2

M41ST87WMX6TR

Package:

SO28 WITH EMBEDDED CRYSTAL

Material Declaration**:

PDF XML

Marketing Status

Active

Package

SO28 WITH EMBEDDED CRYSTAL

Grade

Industrial

RoHS Compliance Grade

Ecopack1

M41ST87WSS6F

Package:

SSOP 20 7.2x5.3

Material Declaration**:

PDF XML

Marketing Status

Active

Package

SSOP 20 7.2x5.3

Grade

Industrial

RoHS Compliance Grade

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.

Sample & Buy

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max
M41ST87WMX6TR Available at 4 distributors

Distributor availability ofM41ST87WMX6TR

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 604 1 Order Now
RS COMPONENTS EUROPE 2264 1 Order Now
ARROW EUROPE 1000 0 Order Now
MOUSER WORLDWIDE 1871 1 Order Now

Distributor reported inventory date: 2020-08-02

Distributor Name

DIGIKEY

Stock

604

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

2264

Min.Order

1

Region

EUROPE Order Now

ARROW

Stock

1000

Min.Order

0

Region

EUROPE Order Now

MOUSER

Stock

1871

Min.Order

1

Region

WORLDWIDE Order Now

Distributor reported inventory date: 2020-08-02

Sample & Buy Buy now
Active
EAR99 NEC Tape And Reel SO28 WITH EMBEDDED CRYSTAL -40 85 3.94 / 1k
MORE INFO

NVRAM size (B):

128

Country of Origin:

PHILIPPINES

M41ST87WSS6F Available at 6 distributors

Distributor availability ofM41ST87WSS6F

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 3155 1 Order Now
RS COMPONENTS EUROPE 1044 1 Order Now
ARROW EUROPE 9450 0 Order Now
ARROW AMERICA 2700 1350 Order Now
MOUSER WORLDWIDE 1121 1 Order Now
ANGLIA Live EUROPE 1000 1 Order Now

Distributor reported inventory date: 2020-08-02

Distributor Name

DIGIKEY

Stock

3155

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

1044

Min.Order

1

Region

EUROPE Order Now

ARROW

Stock

9450

Min.Order

0

Region

EUROPE Order Now

ARROW

Stock

2700

Min.Order

1350

Region

AMERICA Order Now

MOUSER

Stock

1121

Min.Order

1

Region

WORLDWIDE Order Now

ANGLIA Live

Stock

1000

Min.Order

1

Region

EUROPE Order Now

Distributor reported inventory date: 2020-08-02

Sample & Buy Buy now
Active
EAR99 NEC Tape And Reel SSOP 20 7.2x5.3 -40 85
MORE INFO

NVRAM size (B):

128

Country of Origin:

MALAYSIA

M41ST87WMX6TR

Marketing Status

Active

ECCN (US)

EAR99

Budgetary Price (US$)*/Qty

3.94 / 1k

Distributor availability ofM41ST87WMX6TR

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 604 1 Order Now
RS COMPONENTS EUROPE 2264 1 Order Now
ARROW EUROPE 1000 0 Order Now
MOUSER WORLDWIDE 1871 1 Order Now

Distributor reported inventory date: 2020-08-02

Distributor Name

DIGIKEY

Stock

604

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

2264

Min.Order

1

Region

EUROPE Order Now

ARROW

Stock

1000

Min.Order

0

Region

EUROPE Order Now

MOUSER

Stock

1871

Min.Order

1

Region

WORLDWIDE Order Now

Distributor reported inventory date: 2020-08-02

ECCN (EU)

NEC

Packing Type

Tape And Reel

Package

SO28 WITH EMBEDDED CRYSTAL

Operating Temperature (°C)

(min)

-40

(max)

85

Budgetary Price (US$)* / Qty

3.94 / 1k

NVRAM size (B)

128

Country of Origin

PHILIPPINES

M41ST87WSS6F

Marketing Status

Active

ECCN (US)

EAR99

Budgetary Price (US$)*/Qty

Distributor availability ofM41ST87WSS6F

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 3155 1 Order Now
RS COMPONENTS EUROPE 1044 1 Order Now
ARROW EUROPE 9450 0 Order Now
ARROW AMERICA 2700 1350 Order Now
MOUSER WORLDWIDE 1121 1 Order Now
ANGLIA Live EUROPE 1000 1 Order Now

Distributor reported inventory date: 2020-08-02

Distributor Name

DIGIKEY

Stock

3155

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

1044

Min.Order

1

Region

EUROPE Order Now

ARROW

Stock

9450

Min.Order

0

Region

EUROPE Order Now

ARROW

Stock

2700

Min.Order

1350

Region

AMERICA Order Now

MOUSER

Stock

1121

Min.Order

1

Region

WORLDWIDE Order Now

ANGLIA Live

Stock

1000

Min.Order

1

Region

EUROPE Order Now

Distributor reported inventory date: 2020-08-02

ECCN (EU)

NEC

Packing Type

Tape And Reel

Package

SSOP 20 7.2x5.3

Operating Temperature (°C)

(min)

-40

(max)

85

Budgetary Price (US$)* / Qty

NVRAM size (B)

128

Country of Origin

MALAYSIA

(*) 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