MC9S12A128 Datasheet, PDF (78/92 Pages) Motorola, Inc – Microcontroller unit (MCU)

MC9S12A128 Device Guide — V01.01
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----_{⋅--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)
15
10
20
N
Figure A-4 Maximum Bus Clock Jitter Approximation
This is very important to notice with respect to timers, serial modules where a pre-scaler will eliminate the
effect of the jitter to a large extent.
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