User Manual
92
Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
System Control Unit - Digital Modules (SCU-DM)
Figure 28 PLL
Block
Diagram
The reference frequency
f
R
can be selected to be taken either from the internal oscillator
f
INT
or from an
external clock source
f
OSC
.
The PLL uses up to three dividers to set the system frequency
f
sys
in a flexible way. Each of the three dividers
can be bypassed corresponding to the PLL operating mode (based on
f
PLL
):
• Bypassing P, N and K2 dividers; this defines the Prescaler Mode
• Bypassing K1 divider; this defines the Normal Mode
• Bypassing K1 divider and ignoring the P divider; this defines the Freerunning Mode
shows the selectable clock source options.
Normal Mode
In Normal Mode the reference frequency
f
R
is divided down by a factor P, multiplied by a factor N and then
divided down by a factor K2.
The output frequency is given by:
(7.1)
The Normal Mode is selected by the following settings
• PLL_CON.VCOBYP = 0
The Normal Mode is active when
• PLL_CON.VCOBYP = 0
• PLL_CON.OSCDISC = 0
Table 32 Clock
Option
Selection
VCOBYP
OSCDISC
Mode Selected
0
0
Normal Mode
1
x
Prescaler Mode
0
1
Freerunning Mode
PLL_block
f
INT
f
R
M
U
X
Internal
Oscillator
(OSC_PLL)
P-
Divider
VCO
Core
f
OSC
N-
Divider
Lock-
Detection
OSC
WDG
K1-
Divider
K2-
Divider
M
U
X
f
PLL
f
DIV
f
K2
f
K1
O
S
C_
CO
N
.O
S
CS
S
PL
L_
C
O
N
.
VC
O
B
YP
f
VCO
f
P
f
REF
PL
L_
C
O
N
.O
S
CD
IS
C
=
P
N
K2
•
•
f
PLL
f
R