M41ST87W

Active

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

Download datasheet Order Direct
Overview
Sample & Buy
Solutions
Documentation
CAD Resources
Tools & Software
Quality & Reliability
eDesignSuite
Get Started
Partner products
Sales Briefcase
  • 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

Download Download

Recommended for you

All tools & software

    • Part number
      Status
      Description
      Type
      Supplier

      STSW-SRTC001

      Active

      I2C code for Serial RTC

      Clocks and Timers Software ST

      STSW-SRTC002

      Active

      SPI code -Serial RTC

      Clocks and Timers Software ST
      STSW-SRTC001

      Description:

      I2C code for Serial RTC
      STSW-SRTC002

      Description:

      SPI code -Serial RTC

EDA Symbols, Footprints and 3D Models

STMicroelectronics - M41ST87W

Speed up your design by downloading all the EDA symbols, footprints and 3D models for your application. You have access to a large number of CAD formats to fit with your design toolchain.

Symbols

Symbols

Footprints

Footprints

3D model

3D models

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

Part Number
Order from Distributors
Order from ST
Marketing Status
ECCN (US)
ECCN (EU)
Packing Type
Package
Temperature (°C) Budgetary Price (US$)*/Qty
More info
min
max
M41ST87WMX6TR Available at 2 distributors

Distributor availability ofM41ST87WMX6TR

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 3315 1 Order Now
RS COMPONENTS EUROPE 718 1 Order Now

Distributor reported inventory date: 2020-12-04

Distributor Name

DIGIKEY

Stock

3315

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

718

Min.Order

1

Region

EUROPE Order Now

Distributor reported inventory date: 2020-12-04

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 4 distributors

Distributor availability ofM41ST87WSS6F

Distributor Name
Region Stock Min. Order Third party link
DIGIKEY WORLDWIDE 3055 1 Order Now
RS COMPONENTS EUROPE 1044 1 Order Now
MOUSER WORLDWIDE 114 1 Order Now
ANGLIA Live EUROPE 1000 1 Order Now

Distributor reported inventory date: 2020-12-04

Distributor Name

DIGIKEY

Stock

3055

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

1044

Min.Order

1

Region

EUROPE Order Now

MOUSER

Stock

114

Min.Order

1

Region

WORLDWIDE Order Now

ANGLIA Live

Stock

1000

Min.Order

1

Region

EUROPE Order Now

Distributor reported inventory date: 2020-12-04

Free Sample Buy Direct
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 3315 1 Order Now
RS COMPONENTS EUROPE 718 1 Order Now

Distributor reported inventory date: 2020-12-04

Distributor Name

DIGIKEY

Stock

3315

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

718

Min.Order

1

Region

EUROPE Order Now

Distributor reported inventory date: 2020-12-04

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 3055 1 Order Now
RS COMPONENTS EUROPE 1044 1 Order Now
MOUSER WORLDWIDE 114 1 Order Now
ANGLIA Live EUROPE 1000 1 Order Now

Distributor reported inventory date: 2020-12-04

Distributor Name

DIGIKEY

Stock

3055

Min.Order

1

Region

WORLDWIDE Order Now

RS COMPONENTS

Stock

1044

Min.Order

1

Region

EUROPE Order Now

MOUSER

Stock

114

Min.Order

1

Region

WORLDWIDE Order Now

ANGLIA Live

Stock

1000

Min.Order

1

Region

EUROPE Order Now

Distributor reported inventory date: 2020-12-04

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