Electrical Characteristics
1
2
3
N-1
N
0
t
min1
t
nom
t
max1
t
minN
t
maxN
Figure A-2. Jitter Definitions
The relative deviation of t
is at its maximum for one clock period, and decreases towards zero for larger
nom
number of clock periods (N).
Defining the jitter as:
t
(N)
t
(N)
⎛
⎞
⎟
⎠
max
min
J(N) = max 1 –
, 1 –
----------------------
----------------------
⎜
N ⋅ t
N ⋅ t
⎝
nom
nom
For N < 100, the following equation is a good fit for the maximum jitter:
j
1
J(N) = --------
N
J(N)
1
5
10
20
N
Figure A-3. Maximum Bus Clock Jitter Approximation
NOTE
On timers and serial modules a prescaler will eliminate the effect of the jitter
to a large extent.
S12P-Family Reference Manual, Rev. 1.13
524
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