M41T82 datasheet(43/58 Pages) STMICROELECTRONICS

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M41T82 M41T83

Clock operation

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3.16

OTP bit operation (M41T83 in SOX18 package only)

When the OTP (One Time Programmable) bit is set to a '1,' the value in the internal OTP

registers will be transferred to the analog calibration register (12h) and are “Read only.” The

OTP value is programmed by the manufacturer, and will contain the calibration value

necessary to achieve ±5 ppm at room temperature 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

desired value of analog calibration.

When the user sets the OTP bit, they need to wait for approximately 8 ms before the analog

registers transfer the value from the OTP to the analog registers due to the OTP Read

operation.

Table 16.

Initial power-up default values (part 2)

Condition(1)

All other control bits power-up in an undetermined state.

RPT11-15

TI/TP

(2)

M41T83 only.

TIE

(2)

TD1 TD0 RS0 RS1-3

OTP

(2)

A2IE

(2)

RPT21-

AL2E

Initial

Power-up

Subsequent

Power-up(3) (4)

With battery back-up.

UC = unchanged.

M41T82 Datasheet(PDF) 43 Page - STMicroelectronics