Datasheet

Chapter 1 Introduction
MC9S08AC16 Series Data Sheet, Rev. 9
22 Freescale Semiconductor
Table 1-2 lists the functional versions of the on-chip modules.
1.3 System Clock Distribution
Figure 1-2. System Clock Distribution Diagram
Some of the modules inside the MCU have clock source choices. Figure 1-2 shows a simplified clock
connection diagram. The ICG supplies the clock sources:
• ICGOUT is an output of the ICG module. It is one of the following:
— The external crystal oscillator
— An external clock source
— The output of the digitally-controlled oscillator (DCO) in the frequency-locked loop
sub-module
Table 1-2. Versions of On-Chip Modules
Module Version
Analog-to-Digital Converter (ADC) 1
Internal Clock Generator (ICG) 4
Inter-Integrated Circuit (IIC) 2
Keyboard Interrupt (KBI) 1
Serial Communications Interface (SCI) 4
Serial Peripheral Interface (SPI) 3
Timer Pulse-Width Modulator (TPM) 3
Central Processing Unit (CPU) 2
TPM1 TPM2 IIC1 SCI1 SCI2 SPI1
BDCCPU ADC1 RAM FLASH
ICG
ICGOUT
³2
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.
³2
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