Datasheet

MC9S08AC16 Series Data Sheet, Rev. 9
Freescale Semiconductor 127
Chapter 8
Internal Clock Generator (S08ICGV4)
The internal clock generation (ICG) module is used to generate the system clocks for the MC9S08AC16
Series MCU. The analog supply lines V
DDA
and V
SSA
are internally derived from the MCU’s V
DD
and
V
SS
pins. Electrical parametric data for the ICG may be found in Appendix A, “Electrical Characteristics
and Timing Specifications.”
Figure 8-1. System Clock Distribution Diagram
NOTE
Freescale Semiconductor recommends that FLASH location 0xFFBE be
reserved to store a nonvolatile version of ICGTRM. This will allow
debugger and programmer vendors to perform a manual trim operation and
store the resultant ICGTRM value for users to access at a later time.
TPM1 TPM2 IIC1 SCI1 SCI2 SPI1
BDCCPU ADC1 RAM FLASH
ICG
ICGOUT
2
FFE
SYSTEM
LOGIC
BUSCLK
ICGLCLK*
CONTROL
XCLK*
ICGERCLK
* ICGLCLK is the alternate BDC clock source for the MC9S08AC16 Series.
* XCLK is the fixed-frequency clock.
2
FLASH has frequency
requirements for program
and erase operation.
See the Electricals
appendix.
ADC has min and max
frequency requirements.
See the Electricals appendix
and the ADC chapter.
TPM3
COP
RTI
1 kHz
TPMCLK