XC2287 / XC2286 / XC2285
XC2000 Family Derivatives
Preliminary
Electrical Parameters
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 (fSYS) during the operation,
to optimize performance and power consumption of the system. Changing the operating
frequency also changes the consumed switching current, which influences the power
supply. Therefore, while the core voltage is generated by the on-chip EVRs, the
operating frequency may only be changed by factors of 5 maximum, or in steps of
20 MHz maximum, whatever condition is tighter.
To avoid the indicated problems, recommended sequences are provided which ensure
the intended operation of the clock system interacting with the power system.
4.4.2
On-chip Flash Operation
Accesses to the XC228x’s Flash modules are controlled by the IMB.
Built-in prefetching mechanisms optimize the performance for sequential accesses.
Table 18
Flash Characteristics (Operating Conditions apply)
Symbol Limit Values
Parameter
Unit
Min.
CC –
CC –
Typ.
31)
41)
Max.
tbd
Programming time per 128-byte page tPR
Erase time per sector/page
ms
ms
tER
tbd
1) Programming and erase times depend on the internal Flash clock source. The control state machine needs a
few system clock cycles, which only becomes relevant for extremely low system frequencies.
Data Sheet
90
V0.91, 2007-02
Draft Version
INFINEON [ Infineon ]
