XC2200 Derivatives
System Units (Vol. 1 of 2)
System Control Unit (SCU)
User’s Manual
6-2
V2.1, 2008-08
SCU, V1.13
6.1
Clock Generation Unit
The Clock Generation Unit (CGU) allows a very flexible clock generation for the XC2200.
During user program execution the frequency can be programmed for an optimal ratio
between performance and power consumption in the actual application state.
6.1.1
Overview
The CGU can convert a low-frequency external clock to a high-speed system clock or
can create a high-speed system clock without external input.
The CGU consists of a Clock Generator and a Clock Control Unit (CCU).
Figure 6-1
Clock Generation Unit Block Diagram
The input connections of the CGU are described in
The following clock signals are generated:
•
System clock
f
SYS
•
RTC count clock
f
RTC
(
•
Wake-Up Timer (WUT) clock
f
WUT
•
External clock
f
EXT
and
describe which clock signals is generated out of which
selectable clocks.
CGU_Block_Diagram_MR.vsd
Clock Generation Unit (CGU)
CCU
Clock Generator
f
OSC
f
WU
f
CLKIN1
f
CLKIN2
XTAL1
XTAL2
CLKIN1
CLKIN2
f
SYS
RTC
EXTCLK
CC60
f
PLL
f
RTC
f
EXT