M41ST84W View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

M41ST84W

3.0/3.3 V I2C serial RTC with 44 bytes of NVRAM and supervisory functions

STMicroelectronics 

Clock operation

Figure 12. Crystal accuracy across temperature

M41ST84W

Frequency (ppm)

20

0

–20

–40

–60

–80

–100

–120

–140

–160

–40 –30 –20 –10 0

F = K x (T –TO)2

K = –0.036 ppm/°C2 ± 0.006 ppm/°C2

TO = 25°C ± 5°C

10 20 30 40 50 60 70 80

Temperature °C

AI00999b

Figure 13. Clock calibration

NORMAL

POSITIVE

CALIBRATION

NEGATIVE

CALIBRATION

AI00594B

3.4

Setting alarm clock registers

Address locations 0Ah-0Eh contain the alarm settings. The alarm can be configured to go

off at a prescribed time on a specific month, date, hour, minute, or second, or repeat every

year, month, day, hour, minute, or second. It can also be programmed to go off while the

M41ST84W is in the battery backup to serve as a system wakeup call.

Bits RPT5-RPT1 put the alarm in the repeat mode of operation. Table 4 shows the possible

configurations. Codes not listed in the table default to the once per second mode to quickly

alert the user of an incorrect alarm setting.

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