M41ST87WMX6F STMICROELECTRONICS [STMicroelectronics], M41ST87WMX6F Datasheet - Page 33

• Manufacturer Part Number: M41ST87WMX6F
• Description: 5.0 V and 3.3/3.0 V secure serial RTC and NVRAM supervisor with tamper detection and 128 bytes of clearable NVRAM
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

M41ST87Y, M41ST87W
Figure 22. Crystal accuracy across temperature
Figure 23. Calibration waveform
3.3
NORMAL
POSITIVE
CALIBRATION
NEGATIVE
CALIBRATION
Frequency (ppm)
–100
–120
–140
–160
–20
–40
–60
–80
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
M41ST87Y/W is in the battery back-up to serve as a system wake-up call.
Bits RPT5–RPT1 put the alarm in the repeat mode of operation.
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.
When the clock information matches the alarm clock settings based on the match criteria
defined by RPT5–RPT1, the AF (alarm flag) is set. If AFE (alarm flag enable) is also set, the
20
0
–40
–30
–20
–10
0
Doc ID 9497 Rev 8
10
Temperature °C
F
K
= –0.036 ppm/°C
= K x (T – T
20
T
30
O
= 25°C ± 5°C
O
)
2
40
2
± 0.006 ppm/°C
50
60
Table 8 on page 34
2
70
80
Clock operation
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