M41T81MX6 STMicroelectronics, M41T81MX6 Datasheet - Page 5

• Manufacturer Part Number: M41T81MX6
• Description: IC RTC SERIAL W/ALARM 28-SOIC
• Manufacturer: STMicroelectronics
• Type: Clock/Calendar/Alarmr

Specifications of M41T81MX6

• 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 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-2822-5

M41T81
1
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 I
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.
Figure 1.
Table 1.
IRQ/OUT/FT/SQW
V
SDA
SCL
V
V
XO
XI
BAT
CC
SS
Logic diagram
Signal names
Oscillator input
Oscillator output
Interrupt / output driver / frequency test / square wave (open drain)
Serial data input/output
Serial clock input
Battery supply voltage
Supply voltage
Ground
SDA
Doc ID 7529 Rev 10
SCL
XO
XI
V
CC
M41T81
V
SS
V
2
BAT
C interface. The built-in address register is
IRQ/FT/OUT/SQW
Description
AI04613
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