Description

The M41T81 is a low-power serial RTC with a built-in 32.768 kHz oscillator (external crystal controlled).

Features

■ For all new designs other than automotive, use

M41T81S (contact the ST sales office for

automotive grade)

■ 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 switch-over 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