M41T94MH6 STMicroelectronics, M41T94MH6 Datasheet - Page 19

• Manufacturer Part Number: M41T94MH6
• Description: Real Time Clock Serial 512 (64x8)
• Manufacturer: STMicroelectronics

Specifications of M41T94MH6

• Function: Clock, Calendar, Alarm, Timer Interrupt
• Rtc Memory Size: 64 B
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2.7 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Rtc Bus Interface: Serial
• Package / Case: SO-28
• Time Format: HH:MM:SS:hh
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

M41T94
4.3
Note:
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
M41T94 is in the battery backup 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
alarm condition activates the IRQ/FT/OUT pin.
If the address pointer is allowed to increment to the flag register address, an alarm condition
will not cause the interrupt/flag to occur until the address pointer is moved to a different
address. It should also be noted that if the last address written is the “Alarm Seconds,” the
address pointer will increment to the flag address, causing this situation to occur.
To disable the alarm, write '0' to the alarm date register and to RPT1–5. The IRQ/FT/OUT
output is cleared by a READ to the flags register. This READ of the flags register will also
reset the alarm flag (D6; register 0Fh). See
The IRQ/FT/OUT pin can also be activated in the battery backup mode. The IRQ/FT/OUT
will go low if an alarm occurs and both ABE (alarm in battery backup mode enable) and AFE
are set. The ABE and AFE bits are reset during power-up, therefore an alarm generated
during power-up will only set AF. The user can read the flag register at system boot-up to
determine if an alarm was generated while the M41T94 was in the deselect mode during
power-up.
Table 5.
Figure 11. Alarm interrupt reset waveforms
RPT5
1
1
1
1
1
0
ACTIVE FLAG
IRQ/FT/OUT
Figure 12 on page 20
Alarm repeat mode
RPT4
1
1
1
1
0
0
0Eh
RPT3
illustrates the backup mode alarm timing.
1
1
1
0
0
0
0Fh
Figure 11 on page
RPT2
1
1
0
0
0
0
RPT1
1
0
0
0
0
0
19.
Table 5 on page 19
HIGH-Z
Once per second
Clock operations
Once per minute
10h
Once per month
Alarm setting
Once per hour
Once per year
Once per day
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