M41T80M6F Datasheet M41T80M6F, M41T80M6E | P16-P18

Clock operation M41T80

16/27 Doc ID 9074 Rev 5

3.3 Full-time 32 KHz square wave output

The M41T80 offers the user a special 32 KHz square wave function which defaults to output

on the F

32K

pin (pin 3) as long as V

is valid, and the oscillator is running (ST bit = '0'). This

function is available within four seconds of initial power-up and can only be disabled by

setting the 32KE bit to '0' or the ST bit to '1.' If not used, the F

32K

pin should be disconnected

and allowed to float.

Note: The F

32K

pin is an open drain which requires an external pull-up resistor.

3.4 Century bit

Bits D7 and D6 of clock register 03h contain the CENTURY ENABLE bit (CEB) and the

CENTURY bit (CB). Setting CEB to a '1' will cause CB to toggle, either from a '0' to '1' or

from '1' to '0' at the turn of the century (depending upon its initial state). If CEB is set to a '0,'

CB will not toggle.

Table 5. Square wave output frequency

Square wave bits Square wave

RS3 RS2 RS1 RS0 Frequency Units

0000None-

000132.768kHz

00108.192kHz

00114.096kHz

01002.048kHz

01011.024kHz

0110512Hz

0111256Hz

1000128Hz

100164Hz

101032Hz

101116Hz

11008Hz

11014Hz

11102Hz

11111Hz

M41T80 Clock operation

Doc ID 9074 Rev 5 17/27

3.5 Output driver pin

When the AFE bit and SQWE bit are not set, the IRQ/OUT/SQW pin becomes an output

driver that reflects the contents of D7 of the control register. In other words, when D7 (OUT

bit) of address location 08h is a '0,' then the IRQ

/OUT/SQW pin will be driven low.

Note: The IRQ

/OUT/SQW pin is an open drain which requires an external pull-up resistor.

3.6 Preferred power-on default

When powering the device up from ground (0 V), the following register bits are set to a '0'

state: ST; AFE; and SQWE. The following bits are set to a '1' state: OUT and 32KE (see

Table 6: Preferred power-on default values on page 17).

Table 6. Preferred power-on default values

Condition ST OUT AFE SQWE 32KE

Power-up

(1)

1. If V

falls to a voltage, 0 V < V

< 2.0 V, these bits should be rewritten by the user.

0100 1

Maximum rating M41T80

18/27 Doc ID 9074 Rev 5

4 Maximum rating

Stressing the device above the rating listed in the “absolute maximum ratings” table may

cause permanent damage to the device. These are stress ratings only and operation of the

device at these or any other conditions above those indicated in the operating sections of

this specification is not implied. Exposure to absolute maximum rating conditions for

extended periods may affect device reliability. Refer also to the STMicroelectronics SURE

Program and other relevant quality documents.

Table 7. Absolute maximum ratings

Symbol Parameter Value Unit

STG

Storage temperature (V

off, oscillator off) –55 to 125 °C

Supply voltage –0.3 to 7 V

SLD

(1)

1. For SO package, lead-free (Pb-free) lead finish: reflow at peak temperature of 260 °C (the time

above 255 °C must not exceed 30 seconds).

Lead solder temperature for 10 seconds 260 °C

Input or output voltages –0.3 to +6 V

Output current 20 mA

Power dissipation 1 W

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P24 P25-P27

M41T80M6F

Mfr. #:

Buy M41T80M6F

Manufacturer:

STMicroelectronics

Description:

Real Time Clock Serial 160 (20x8)

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M41T80M6F

M41T80M6F

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