MC9S12E256 Datasheet, PDF (576/602 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

Appendix A Electrical Characteristics
0
1
2
3
N-1
N
t_min1
t_nom
t_max1
t_minN
t_maxN
Figure A-3. Jitter Definitions
The relative deviation of t_nom is at its maximum for one clock period, and decreases towards zero for larger
number of clock periods (N).
Defining the jitter as:
J(N)
=
⎛
max⎜
⎝
1 – ^t-N-m----_â‹--a-t--xn----⁽_o--N--m---⁾ ,
1
–
N-t--m---⋅^{--i-t-n-n---(-o-N---m--)-}
⎞
⎟
⎠
For N < 100, the following equation is a good fit for the maximum jitter:
J(N)
=
--^j--¹---
N
+
j2
J(N)
1
5
10
20
N
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.
MC9S12E256 Data Sheet, Rev. 1.08
576
Freescale Semiconductor