M41T81SM6F STMicroelectronics, M41T81SM6F Datasheet - Page 6

• Manufacturer Part Number: M41T81SM6F
• Description: IC RTC SERIAL W/ALARM 8SOIC
• Manufacturer: STMicroelectronics
• Type: Clock/Calendar/Alarmr

Specifications of M41T81SM6F

• Memory Size: 20B
• Time Format: HH:MM:SS:hh (24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Function: Clock/Calendar/Alarm/Timer Interrupt
• Rtc Memory Size: 20 Byte
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2.7 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Rtc Bus Interface: Serial (I2C)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-4684-2

Description
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Description
The M41T81S 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, bi-directional I
incremented automatically after each WRITE or READ data byte.
The M41T81S 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 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 M41T81S is supplied in either an 8-pin SOIC or an 18-pin (MY), 300 mil SOIC package
which includes an embedded 32 KHz crystal.
The 18-pin, embedded crystal SOIC requires only a user-supplied battery to provide non-
volatile operation.
Figure 1.
1. For SO8 package only
Logic diagram
XO
SDA
XI
SCL
Doc ID 10773 Rev 6
(1)
(1)
V CC
M41T81S
V SS
V BAT
2
C interface. The built-in address register is
IRQ/FT/OUT/SQW
M41T81S
AI09160