![Infineon Technologies TC1784 User Manual Download Page 197](http://html.mh-extra.com/html/infineon-technologies/tc1784/tc1784_user-manual_2055446197.webp)
TC1784
System Control Unit (SCU)
User´s Manual
3-14
V1.1, 2011-05
32-bit SCU, V1.18
of the K2-divider has no impact on the VCO Lock status but still changes the PLL output
frequency.
Note: Changing the system operation frequency by changing the value of the K2-Divider
has a direct coupling to the power consumption of the device. Therefore this has
to be done carefully.
When the frequency of the Normal Mode should be modified or entered the following
sequence should be followed:
First the Prescaler Mode should be configured and entered. For more details see the
Prescaler Mode.
The NMI trap generation for the VCO Lock should be disabled.
While the Prescaler Mode is used the Normal Mode can be configured and checked for
a positive VCO Lock status. The first target frequency of the Normal Mode should be
selected in a way that it matches or is only slightly higher as the one used in the
Prescaler Mode. This avoids big changes in the system operation frequency and
therefore power consumption when switching later from Prescaler Mode to Normal
Mode. The P and N divider should be selected in the following way:
•
Selecting P and N in a way that
f
VCO
is in the lower area of its allowed values leads
to a slightly reduced power consumption but to a slightly increased jitter
•
Selecting P and N in a way that
f
VCO
is in the upper area of its allowed values leads
to a slightly increased power consumption but to a slightly reduced jitter
After the P, N, and K2 dividers are updated for the first configuration the indication of the
VCO Lock status should be await (PLLSTAT.VCOLOCK = 1).
Note: It is recommended to reset the VCO Lock detection (PLLCON0.RESLD = 1) after
the new values of the dividers are configured to get a defined VCO lock check
time.
When this happens the switch from Prescaler Mode to Normal Mode can be done.
Normal Mode is requested by clearing PLLCON.VCOBYP. The Normal Mode is entered
when the status bit PLLSTAT.VCOBYST is cleared.
Now the Normal Mode is entered. The NMI status flag for the VCO Lock trap should be
cleared and then enabled again. The intended PLL output target frequency can now be
configured by changing only the K2-Divider.
Depending on the selected divider value of the K2-Divider the duty cycle of the clock is
selected. This can have an impact for the operation with an external communication
interface. The duty cycles values for the different K2-divider values are defined in the
Data Sheet. This can result in multiple changes of the K2-Divider to avoid to big
frequency changes. Between the update of two K2-Divider values 6 cycles of
f
PLL
should
be waited.
PLL VCO Lock Detection
Summary of Contents for TC1784
Page 1: ...User s Manual V1 1 2011 05 Microcontrollers TC1784 32 Bit Single Chip Microcontroller ...
Page 3: ...User s Manual V1 1 2011 05 Microcontrollers TC1784 32 Bit Single Chip Microcontroller ...
Page 950: ...TC1784 Direct Memory Access Controller DMA User s Manual 11 132 V1 1 2011 05 DMA V3 03 ...
Page 1949: ...TC1784 General Purpose Timer Array GPTA v5 User s Manual 21 297 V1 1 2011 05 GPTA v5 V1 14 ...
Page 2350: ...w w w i n f i n e o n c o m Published by Infineon Technologies AG Doc_Number ...