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M41T00AUDD1F

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42
M41T00AUD Clock calibration
Doc ID 13480 Rev 5 25/42
Example 2:
Sign is 0 and N is 3 (00010b). The 16-minute interval will be:
3 * 513 + (60-3) * 512 + 15 * 60 * 512 = 491523 cycles long out of a possible
512 * 60 * 16 = 491520 cycles of the 512 Hz clock in an 16-minute span.
This gives a net correction of (491520-491523) / 491520 = +6.104 ppm
Therefore, each calibration step has an effect on clock accuracy of either -4.068 or +2.034
ppm. Assuming that the oscillator is running at exactly 32,768 Hz, each of the 31 steps in
the calibration byte would represent subtracting 10.7 or adding 5.35 seconds per month,
which corresponds to a total range of –5.5 or +2.75 minutes per month.
Note: The modified pulses are not observable on the frequency test (FT) output, nor will the effect
of the calibration be measurable real-time, due to the periodic nature of the error
compensation.
Clock calibration M41T00AUD
26/42 Doc ID 13480 Rev 5
Table 6. Digital calibration values
Calibration value
DC4-DC0
Calibration result, in ppm, rounded to the nearest integer
Decimal Binary
Slowing
sign DCS = 0
Speeding
sign DCS = 1
0 00000 + 0 ppm – 0 ppm
1 00001 + 2 ppm – 4 ppm
2 00010 + 4 ppm – 8 ppm
3 00011 + 6 ppm – 12 ppm
4 00100 + 8 ppm – 16 ppm
5 00101 + 10 ppm – 20 ppm
6 00110 + 12 ppm – 24 ppm
7 00111 + 14 ppm – 28 ppm
8 01000 + 16 ppm – 33 ppm
9 01001 + 18 ppm – 37 ppm
10 01010 + 20 ppm – 41 ppm
11 01011 + 22 ppm – 45 ppm
12 01100 + 24 ppm – 49 ppm
13 01101 + 26 ppm – 53 ppm
14 01110 + 28 ppm – 57 ppm
15 01111 + 31 ppm – 61 ppm
16 10000 + 33 ppm – 65 ppm
17 10001 + 35 ppm – 69 ppm
18 10010 + 37 ppm – 73 ppm
19 10011 + 39 ppm – 77 ppm
20 10100 + 41 ppm – 81 ppm
21 10101 + 43 ppm – 85 ppm
22 10110 + 45 ppm – 90 ppm
23 10111 + 47 ppm – 94 ppm
24 11000 + 49 ppm – 98 ppm
25 11001 + 51 ppm – 102 ppm
26 11010 + 53 ppm – 106 ppm
27 11011 + 55 ppm – 110 ppm
28 11100 + 57 ppm – 114 ppm
29 11101 + 59 ppm – 118 ppm
30 11110 + 61 ppm – 122 ppm
31 11111 + 63 ppm – 126 ppm
N +N/491520 (per minute) –N/245760 (per minute)
M41T00AUD Clock calibration
Doc ID 13480 Rev 5 27/42
Figure 15. Crystal accuracy across temperature
AI00999b
–160
0 10203040506070
Frequency (ppm)
Temperature °C
80–10–20–30–40
–100
–120
–140
–40
–60
–80
20
0
–20
DF
= K x (T –T
O
)
2
K = –0.036 ppm/˚C
2
± 0.006 ppm/˚C
2
T
O
= 25˚C ± 5˚C
F
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42

M41T00AUDD1F

Mfr. #:
Buy M41T00AUDD1F
Manufacturer:
STMicroelectronics
Description:
Real Time Clock SERIAL RTC W/AUDIO
Lifecycle:
New from this manufacturer.
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