Datasheet

Clock operation M41T93
42/56 DocID12615 Rev 8
3.15 Initial power-on defaults
Upon initial application of power to the device, the register bits will initially power-on in the
state indicated in Table 13 and Table 14.
Table 13. Initial power-on default values (part 1)
Table 14. Initial power-up default values (part 2)
3.16 OTP bit operation (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)
(V
CC
only) at room temperature after two SMT
reflows. This clock accuracy can 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 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.
Condition
(1)
1. All other control bits power-up in an undetermined state
ST CB1 CB0 OUT FT
DCS
ACS
Digital
calib.
Analog
calib.
OFIE Watchdog
(2)
2. BMB0-BMB4, RB0, RB1
A1IE SQWE ABE
Initial
power-up
000 100 0 0 0 0 0 1 0
Subsequent
power-up
(3)(4)
3. With battery backup
4. UC = Unchanged
UC UC UC UC 0 UC UC UC UC 0 UC UC UC
Condition
(1)
1. All other control bits power-up in an undetermined state
RPT11-15 HT OF TE TI/TP TIE TD1 TD0 RS0 RS1-3 OTP RPT21-25 AL2E
Initial
power-up
011000111000 0
Subsequent
power-up
(2)(3)
2. With battery backup
3. UC = Unchanged
UC 1 UC 0 UC UC UC UC UC UC UC UC UC
a. Max. value = +12 ppm / –5 pmm based on limited data