M41T81 - ST Microelectronics

M41T81 Serial access real-time clock

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 transferr.

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 t.