MC9S12A128 MOTOROLA [Motorola, Inc], MC9S12A128 Datasheet - Page 76

• Manufacturer Part Number: MC9S12A128
• Description: Microcontroller unit (MCU)
• Manufacturer: MOTOROLA [Motorola, Inc]

A.5.3 Phase Locked Loop
The oscillator provides the reference clock for the PLL. The PLL´s Voltage Controlled Oscillator (VCO)
is also the system clock source in self clock mode.
A.5.3.1 XFC Component Selection
This section describes the selection of the XFC components to achieve a good filter characteristics.
The following procedure can be used to calculate the resistance and capacitance values using typical
values for K
The VCO Gain at the desired VCO output frequency is approximated by:
The phase detector relationship is given by:
i
ch
is the current in tracking mode.
f
osc
1
, f
1
and i
refdv+1
ch
1
from
Figure A-2 Basic PLL Functional Diagram
f
ref
Table
A-16.
K
f
cmp
V
K
=
Loop Divider
Detector
K
=
Phase
1
synr+1
K
–
e
i
1
ch
--------------------------- -
C
f
K 1 1V
1
s
–
K
f
V
vco
V
DDPLL
R
MC9S12A128 Device Guide — V01.01
1
2
C
p
VCO
K
V
f
vco
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