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.
|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 MB|
|AN3060: Applications guide for serial real-time clocks (RTCs)||3.0||878 KB|
|AN1011: Battery technology used in NVRAM and real-time clock (RTC) products from ST||4.0||248 KB|
|AN1879: How to use the M41ST87W tamper detect and RAM clear||5.0||107 KB|
|AN934: How to use the digital calibration feature in TIMEKEEPER® and serial real-time clock (RTC) products||4.1||123 KB|
|AN1216: Implementing a periodic alarm with TIMEKEEPER® and serial real-time clocks (RTCs)||2.0||192 KB|
|AN4641: Integrating TIMEKEEPER® and real-time clock supervisor functions||1.0||479 KB|
|AN923: Managing century information using serial real-time clocks and TIMEKEEPER® NVRAMs||4.0||142 KB|
|AN1572: Power-down time-stamp function in serial real-time clocks (RTCs)||2.0||171 KB|
|AN1336: Power-fail comparator for NVRAM supervisory devices||2.0||127 KB|
|AN1012: Predicting the battery life and data retention period of NVRAMs and serial RTCs||4.1||439 KB|
|Ibis model||1.0||14 KB|
|Serial real-time clock ICs||1.0||827 KB|
|Part Number||Package||Packing Type||Operating Temperature (°C) (min)||Operating Temperature (°C) (max)||Marketing Status||Unit Price (US$) *||Quantity||NVRAM size (B)||ECCN (EU)||ECCN (US)||Country of Origin||More info||Order from ST||Order from Distributors|
|M41ST87WMX6TR||SO28 WITH EMBEDDED CRYSTAL||Tape And Reel||-40||85||Active : Product is in volume production||3.94||1000||128||NEC||EAR99||MALAYSIA||MORE INFO||Get Sample Add to cart||DISTRIBUTOR AVAILABILITY|
|M41ST87WSS6F||SSOP 20 7.2x5.3||Tape And Reel||-40||85||Active : Product is in volume production||2.94||1000||128||NEC||EAR99||MALAYSIA||MORE INFO||Get Sample Add to cart||DISTRIBUTOR AVAILABILITY|
|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|
(**) 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.