XC228X_08 Datasheet, PDF (103/125 Pages) Infineon Technologies AG – 16/32-Bit Single-Chip Microcontroller with 32-Bit Performance

XC2287 / XC2286 / XC2285
XC2000 Family Derivatives
Electrical Parameters
Wakeup Clock
When wakeup operation is selected (SYSCON0.CLKSEL = 00_B), the system clock is
derived from the low-frequency wakeup clock source:
f_SYS = f_WU.
In this mode, a basic functionality can be maintained without requiring an external clock
source and while minimizing the power consumption.
Selecting and Changing the Operating Frequency
When selecting a clock source and the clock generation method, the required
parameters must be carefully written to the respective bitfields, to avoid unintended
intermediate states.
Many applications change the frequency of the system clock (f_SYS) during operation in
order to optimize system performance and power consumption. Changing the operating
frequency also changes the switching currents, which influences the power supply.
To ensure proper operation of the on-chip EVRs while they generate the core voltage,
the operating frequency shall only be changed in certain steps. This prevents overshoots
and undershoots of the supply voltage.
To avoid the indicated problems, recommended sequences are provided which ensure
the intended operation of the clock system interacting with the power system.
Please refer to the Programmer’s Guide.
Data Sheet
101
V2.1, 2008-08