Appendix A Electrical Characteristics
MC9S12XDP512 Data Sheet, Rev. 2.11
Freescale Semiconductor 949
The relative deviation of tnom is at its maximum for one clock period, and decreases towards zero for larger
number of clock periods (N).
Defining the jitter as:
For N < 1000, the following equation is a good fit for the maximum jitter:
Figure A-5. Maximum Bus Clock Jitter Approximation
This is very important to notice with respect to timers, serial modules where a prescaler will eliminate the
effect of the jitter to a large extent.
JN() max 1
tmax N()
Nt
nom
-----------------------
1
tmin N()
Nt
nom
-----------------------
,
⎝⎠
⎜⎟
⎛⎞
=
JN() j1
N
-------- j2
+=
1 5 10 20 N
J(N)