M41T81中文资料串行实时时钟（RTC），具有报警功能数据手册ST规格书

描述 Description

The M41T81 is a low-power serial RTC with a built-in 32.768 kHz oscillator (external crystal controlled). Eight bytes of the SRAM are used for the clock/calendar function and are configured in binary-coded decimal (BCD) format. An additional 12 bytes of SRAM provide status/control of alarm, watchdog and square wave functions. 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 M41T81 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 supply when a power failure occurs.

Functions available to the user include a non-volatile, time-of-day clock/calendar, alarm interrupts, watchdog timer and programmable square wave output. 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 - valid until year 2100), 30 and 31 day months are made automatically.

The M41T81 is supplied in an 8-pin SOIC.

特性 Features

• For all new designs use M41T81S
• Counters for tenths/hundredths of seconds, seconds, minutes, hours, day, date, month, year, and century
• 32 KHz crystal oscillator integrating load capacitance (12.5 pF) providing exceptional oscillator stability and high crystal series resistance operation
• Serial interface supports I2C bus (400 kHz protocol)
• Ultra-low battery supply current of 0.6 μA (typ at 3 V)
• 2.0 to 5.5 V clock operating voltage
• Automatic switchover and deselect circuitry (for 3 V application select M41T81S datasheet)
• Power-down time stamp (HT bit) allowing determination of time elapsed in battery backup
• Programmable alarm and interrupt function (valid even during battery backup mode)
• Accurate programmable watchdog timer (from 62.5 ms to 128 s)
• Software clock calibration to compensate crystal deviation due to temperature
• Operating temperature of –40 to 85 °C
• ECOPACK®package available

简介

M41T81属于集成电路（IC）的实时时钟。由制造生产的M41T81实时时钟实时时钟 (RTC) 为几乎所有需要保持精确时间的电子设备提供时间和/或日期信息。时钟类型有二进制计数器、时钟/日历/监控器、历时计时器、幻时钟芯片、便携式系统控制器、温度记录器、时间事件记录器和计时器时钟外设。其包含 2 B 至 2 MB 不等的存储器，接口选项有 I2C、并行、串行、SPI、1 线式、2 线式、3 线式和 4 线式。