S912XHY128F0VLM Datasheet, PDF (749/802 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

Electrical Characteristics
control loop resulting in a clock jitter. This jitter affects the real minimum and maximum clock periods as
illustrated in Figure A-4.
0
1
2
3
N-1
N
t_min1
t_nom
t_max1
t_minN
t_maxN
Figure A-4. 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-----_{⋅-a--t-nx----}(_o--N--m---)
,
1
–
N-t--m---⋅^{--i-t-n-n---(-o-N---m--)-}
⎞
⎟
⎠
For N < 1000, the following equation is a good fit for the maximum jitter:
J(N)
=
---^j--¹---
N
+
j₂
J(N)
1
5
10
20
N
Figure A-5. Maximum bus clock jitter approximation
MC9S12XHY-Family Reference Manual, Rev. 1.01
Freescale Semiconductor
749