MC9S08AC60 Datasheet, PDF (23/348 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 1 Introduction
— 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.
• FFE is a control signal generated inside the ICG. If the frequency of ICGOUT > 4 × the frequency
of ICGERCLK, this signal is a logic 1 and the fixed-frequency clock will be ICGERCLK/2.
Otherwise the fixed-frequency clock will be BUSCLK.
• ICGLCLK — Development tools can select this internal self-clocked source (~ 8 MHz) to speed
up BDC communications in systems where the bus clock is slow.
• ICGERCLK — External reference clock can be selected as the real-time interrupt clock source.
Can also be used as the ALTCLK input to the ADC module.
MC9S08AC60 Series Data Sheet, Rev. 2
Freescale Semiconductor
23