M41TC8025AMC5F datasheet(17/41 Pages) STMICROELECTRONICS

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M41TC8025

Operation

The RESET bit in the control register 0Fh is related to the clock counter operations.

If RESET=1, the internal clock divider below 4 KHz will be stopped and the RTC module's

internal counter value will be cleared. The updating of seconds, minutes, hours, day-of-

week, date (day of month), month and year registers will be stopped. As a result, the alarm

function, the time update interrupt and part of the fixed-cycle interrupt (clock source <4 KHz)

will be stopped.

If RESET=0, the clock divider below 4 KHz operates normally. All the updates of the clock

and calendar and interrupts return to normal operation.

Once the RESET bit is set to 1, it will be automatically cleared to 0 upon a STOP condition,

a RE-START condition or the 0.95 second I2C timeout occurrence.

2.4.4

Temperature compensation

The M41TC8025 RTC incorporates a temperature sensor to monitor the device temperature

and compensate the internal clock source so that accurate timekeeping over the extended

temperature range of -45 to +70 °C or the industrial temperature range of -40 to +85 °C is

maintained. The compensation period can be configured by the user to 0.5 s, 2 s, 10 s or

30 s. The related register bits (CSEL1 and CSEL0, highlighted in bold) are shown in

Table 10 and the detailed configuration is given in Table 11.

2.5

Programmable frequency output on FOUT pin

The M41TC8025 RTC provides programmable accurate 1 Hz, 1,024 Hz (1 KHz) and

32,768 Hz (32 KHz) square wave output on the FOUT pin. The user can configure the

output frequency through the FSEL1 and FSEL0 bits in the 0Dh register. The FOUT pin is a

CMOS output and controlled by the FOE pin.

If the FOE pin is logic high, the FOUT output is enabled. If the FOE pin is logic low, the

FOUT output is disabled and is Hi-Z.

Table 10. Temperature compensation bits in control register 0Fh

Address

Function

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

0Fh

Control register CSEL1 CSEL0

UIE

TIE

AIE

RESET

Table 11. Temperature compensation period configuration

CSEL1

CSEL0

Compensation period

Comment

0.5 s

2 s

Default

10 s

30 s

Obsolete

Product(s)

- Obsolete

Product(s)

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