saf-xc866-4rri3v Infineon Technologies Corporation, saf-xc866-4rri3v Datasheet - Page 62

• Manufacturer Part Number: saf-xc866-4rri3v
• Description: 8-bit Single-chip Microcontroller
• Manufacturer: Infineon Technologies Corporation

The clock system provides three ways to generate the system clock:
PLL Base Mode
The system clock is derived from the VCO base (free running) frequency clock divided
by the K factor.
Prescaler Mode (VCO Bypass Operation)
In VCO bypass operation, the system clock is derived from the oscillator clock, divided
by the P and K factors.
PLL Mode
The system clock is derived from the oscillator clock, multiplied by the N factor, and
divided by the P and K factors. Both VCO bypass and PLL bypass must be inactive for
this PLL mode. The PLL mode is used during normal system operation. .
Table 3-1
selection.
Table 3-1
OSCDISC
0
0
1
1
Note: When oscillator clock is disconnected from PLL, the clock mode is PLL Base mode
System Frequency Selection
For the XC866, the values of P and K are fixed to “1” and “2”, respectively. In order to
obtain the required system frequency, f
for different oscillator inputs.
obtained for the different oscillator sources.
Data Sheet
regardless of the setting of VCOBYP bit.
shows the settings of bits OSCDISC and VCOBYP for different clock mode
Clock Mode Selection
VCOBYP
0
1
0
1
Table 21
f
f
SYS
SYS
f
SYS
=
=
=
provides examples on how f
f
f
sys
VCObase
OSC
f
Clock Working Modes
PLL Mode
Prescaler Mode
PLL Base Mode
PLL Base Mode
OSC
, the value of N can be selected by bit NDIV
58
×
×
-------------
P
-------------
P K
N
×
×
×
1
K
--- -
K
1
Functional Description
sys
= 80 MHz can be
V1.2, 2007-10
XC866