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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.主な特徴
- 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
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品質 & 信頼性
| 製品型番 | Marketing Status | パッケージ | グレード | RoHSコンプライアンスグレード | 材料宣誓書** |
|---|---|---|---|---|---|
| M41ST87WMX6TR |
量産中
|
SO28 WITH EMBEDDED CRYSTAL | インダストリアル | Ecopack1 | |
| M41ST87WSS6F |
量産中
|
SSOP 20 7.2x5.3 | インダストリアル | Ecopack2 |
(**) st.comで提供している材料宣誓書は、パッケージ･ファミリ内で最も一般的に使用されているパッケージに基づく汎用ドキュメントの場合があります。そのため、特定の製品では100%正確ではない可能性があります。特定の製品情報については、セールスサポートまでお問い合わせください
サンプル & 購入
| 製品型番 | 販売代理店からオーダー | STからオーダー | 製品ステータス | ECCN (US) | ECCN (EU) | 梱包タイプ | パッケージ | 温度（℃） | NVRAM size (B) | Country of Origin | Budgetary Price (US$)*/Qty | 詳細情報 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 最小 | 最大 | |||||||||||||
| M41ST87WMX6TR | 4 distributors |
量産中
|
EAR99 | NEC | Tape And Reel | SO28 WITH EMBEDDED CRYSTAL | -40 | 85 | 128 | PHILIPPINES | 3.94 / 1k | |||
| M41ST87WSS6F | 6 distributors | サンプル & 購入 購入 |
量産中
|
EAR99 | NEC | Tape And Reel | SSOP 20 7.2x5.3 | -40 | 85 | 128 | MALAYSIA | |||
製品ステータス
量産中ECCN (US)
EAR99Budgetary Price (US$)*/Qty
3.94 / 1k（*）概算用の希望小売単価（US$）です。現地通貨でのお見積りについては、STのセールス･オフィスまたは販売代理店までお問い合わせください。
