ST Life.augmented

M41ST87W

Serial real-time clock (RTC) supervisor
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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.

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Errata Sheet
pdf データシート
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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 VTHS = 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 VTHS = 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

回路図

デザイン・リソース

トップ

Technical Documentation

Product Specifications

Description Version Size
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
10.0 782 KB

Application Notes

Description Version Size
pdf
AN1011: Battery technology used in NVRAM and real-time clock (RTC) products from ST
4.0 248 KB
pdf
AN1012: Predicting the battery life and data retention period of NVRAMs and serial RTCs
4.0 439 KB
pdf
AN1216: Implementing a periodic alarm with TIMEKEEPER® and serial real-time clocks (RTCs)
2.0 193 KB
pdf
AN1336: Power-fail comparator for NVRAM supervisory devices
2.0 128 KB
pdf
AN1572: Power-down time-stamp function in serial real-time clocks (RTCs)
2.0 171 KB
pdf
AN1879: How to use the M41ST87W tamper detect and RAM clear
5.0 107 KB
pdf
AN3060: Applications guide for serial real-time clocks (RTCs)
2.1 370 KB
pdf
AN923: Managing century information using serial real-time clocks and TIMEKEEPER® NVRAMs
3.0 195 KB
pdf
AN934: How to use the digital calibration feature in TIMEKEEPER® and serial real-time clock (RTC) products
4.1 123 KB

HW Model & CAD Libraries

HW Model & CAD Libraries

Description Version Size
zip
Ibis model
2.1 15 KB

Related Tools and Software

Related Tools and Software

製品型名 Description
STSW-SRTC001 I2C code for Serial RTC
STSW-SRTC002 SPI code -Serial RTC

Publications and Collaterals

Brochure

Description Version Size
pdf
Serial real-time clock ICs
827 KB

Quality & Reliability

Product Certification

Description Version Size
pdf
Products Underwriter Laboratories (UL) Information
1.0 548 KB

サンプル& 購入

トップ
製品型名 Marketing StatusPackagePacking TypeOperating Temperature (min) Operating Temperature (max) NVRAM sizeAutomotive GradeOrder From STUnit Price (US$)*
@ 1000
Distributor AvailabilityRoHS Compliance GradeDownload
Material Declaration**
M41ST87WMX6TRActiveSO28 WITH EMBEDDED CRYSTALTape And Reel-4085128_-4.12Distributor reported inventory date: 2014-09-02
Distributor NameRegionStockMin. order
ARROWOrder NowAMERICA107391000
AVNETOrder NowAMERICA8970
DIGIKEYOrder NowWORLDWIDE13861
FUTUREOrder NowWORLDWIDE239131
MOUSEROrder NowWORLDWIDE4821
Ecopack1PDF
XML
M41ST87WSS6FActiveSSOP 20 7.2x5.3Tape And Reel-4085128_-3.03Distributor reported inventory date: 2014-09-02
Distributor NameRegionStockMin. order
ARROWOrder NowEUROPE108000
DIGIKEYOrder NowWORLDWIDE6141
MOUSEROrder NowWORLDWIDE13081
Ecopack2PDF
XML

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(**)弊社ホームページで入手できるMaterial Declaration(材料宣誓書)のフォームは、各パッケージ・タイプで最も一般的に使用されるパッケージに基づいた包括的な文書です。そのため、特定のデバイスについて100%正確ではない可能性があります。特定のデバイスに関する情報については、 弊社セールスオフィス にお問合せ下さい。
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