M41T81SMY6E STMicroelectronics, M41T81SMY6E Datasheet - Page 17

• Manufacturer Part Number: M41T81SMY6E
• Description: IC RTC SER W/ALARMS 18-SOIC
• Manufacturer: STMicroelectronics
• Type: Clock/Calendar/Alarmr

Specifications of M41T81SMY6E

• Memory Size: 20B
• Time Format: HH:MM:SS:hh (24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 18-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

M41T81S
Setting alarm clock registers
The IRQ/FT/OUT/SQW pin is an open drain output which requires a pull-up resistor to V
for proper operation. A 500-10k resistor is recommended in order to control the rise time.
The FT bit is cleared on power-down.
Figure 11. Crystal accuracy across temperature
Figure 12. Clock calibration
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
M41T81S is in the battery backup mode 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.
NORMAL
POSITIVE
CALIBRATION
NEGATIVE
CALIBRATION
Frequency (ppm)
–100
–120
–140
–160
–20
–40
–60
–80
20
0
–40
–30
–20
–10
Doc ID 10773 Rev 6
0
10
Temperature °C
ΔF = K x (T – T
F
K
= –0.036 ppm/°C
20
30
T
O
= 25°C ± 5°C
O
)
2
40
2
± 0.006 ppm/°C
Table 3 on page 19
50
60
2
Clock operation
70
80
shows
AI00594B
AI07888
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