M41T80

Summary description

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Summary description

The M41T80 is a low power Serial RTC with a built-in 32.768kHz oscillator (external crystal

controlled). Eight registers (see Table 3: Clock register map on page 14) are used for the

clock/calendar function and are configured in binary coded decimal (BCD) format. An

additional 12 registers provide status/control of Alarm, 32kHz output, and Square Wave

interface. The built-in address register is incremented automatically after each WRITE or

READ data byte.

Functions available to the user include a time-of-day clock/calendar, Alarm interrupts, 32kHz

output, 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 M41T80 is supplied in an 8-pin SOIC.

Figure 1.

Logic diagram

Table 1.

Signal names

XI

Oscillator input

XO

Oscillator output

IRQ/OUT/SQW

Interrupt / output driver / square wave (open drain)

SDA

Serial data input/output

SCL

Serial clock input

32kHz square wave output (open drain)

Supply voltage

Ground

SCL

VCC

M41T80

VSS

SDA

F32k

IRQ/OUT/SQW

XI

XO

AI07005