M41T82 datasheet(49/64 Pages) STMICROELECTRONICS

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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 (VCC 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

M41T82 Datenblatt(PDF) 49 Page - STMicroelectronics