Datasheet

DocID012578 Rev 16 49/64
M41T82, M41T83 Clock operation
3.17 OTP bit operation (M41T83 in SOX18 package only)
Using the factory-supplied analog calibration value
When the OTP (one time programmable) bit is set to a 1, the factory calibration value in the
internal OTP register will be transferred to the analog calibration register (12h) and is “read
only.” The OTP value is programmed by the manufacturer, and will contain the value
necessary to achieve typically ±5 ppm
(a)
at room temperature (V
CC
only) after two SMT
reflows. This clock accuracy can then be guaranteed to drift no more than ±3 ppm the first
year, and ±1 ppm for each following year due to crystal aging.
If the OTP bit is set to 0, the analog calibration register will become a WRITE/READ register
and function like an ordinary register, allowing the user to implement any desired value of
analog calibration.
When the user sets the OTP bit, they must wait for approximately 8 ms while the device
transfers the OTP value into the analog calibration register.
a. Max. value = +12 ppm / –5 ppm based on limited data