M41T82-83-93 series RTCs

AN2678

4/16

Figure 2.

Timing uncertainty

The first cycle of the sampled (bottom) waveform has the period

Similarly, the second cycle has the period

For both cycles together, the total period is

This shows that the uncertainty between all the samples (except the first and last) subtracts

out of the total with the result that only the uncertainty of the first and last cycles remains.

multiple samples of the 512 Hz signal, as shown in Figure 3. So, by measuring several

consecutive samples of the 512 Hz signal, the uncertainty can be minimized to an

acceptable level.

TCLK

FT = 512Hz

FT after

sampling

ai13996

1

2

FT

FTS1

ε

ε

Τ

Τ

Τ

Τ

−

+

=

2

3

FT

FTS2

ε

ε

Τ

Τ

Τ

Τ

−

+

=

3

1

FT

2

3

1

2

FT

FTS2

FTS1

ε

ε

ε

ε

ε

ε

Τ

Τ

Τ

2

Τ

Τ

Τ

Τ

Τ

2

Τ

Τ

+

−

×

=

−

+

−

+

×

=

+