Datasheet

Chapter 1 Device Overview
MC9S08GB60A Data Sheet, Rev. 2
Freescale Semiconductor 21
Table 1-2 lists the functional versions of the on-chip modules.
1.4 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
Control bits inside the ICG determine which source is connected.
Table 1-2. Block Versions
Module Version
Analog-to-Digital Converter (ATD) 3
Internal Clock Generator (ICG) 2
Inter-Integrated Circuit (IIC) 1
Keyboard Interrupt (KBI) 1
Serial Communications Interface (SCI) 1
Serial Peripheral Interface (SPI) 3
Timer Pulse-Width Modulator (TPM) 1
Central Processing Unit (CPU) 2
ATD has min and max
frequency requirements. See
Chapter 1, “Device Overview” and
Appendix A, “Electrical Characteristics.
Flash has frequency
requirements for program
and erase operation.
See Appendix A, “Electrical
Characteristics.
* ICGLCLK is the alternate BDC clock source for the MC9S08GBxxA/GTxxA.
TPM1 TPM2 IIC1 SCI1 SCI2 SPI1
BDC
CPU
ATD1
RAM FLASH
ICG
ICGOUT
÷2
FFE
SYSTEM
LOGIC
BUSCLK
ICGLCLK*
CONTROL
FIXED FREQ CLOCK (XCLK)
ICGERCLK
RTI
÷2