Fujitsu 8FX

MB95630H Series
20 FUJITSU SEMICONDUCTOR LIMITED MN702-00009-2v0-E
CHAPTER 3 CLOCK CONTROLLER
3.1 Overview
■ Clock Modes
There are five clock modes:
• Main clock mode
• Main CR clock mode
• Main CR PLL clock mode
• Subclock mode
• Sub-CR clock mode.
Table 3.1-1 shows the relationships between the clock modes and the machine clock (operating
clock for the CPU and peripheral functions).
In any clock mode, the frequency of a selected clock can be divided.
Table 3.1-1 Clock Modes and Machine Clock Selection
Clock mode Machine clock
Main clock mode The machine clock is generated by dividing the main clock by two.
Main CR clock mode The machine clock is generated from the main CR clock.
Main CR PLL clock mode
The machine clock is generated by multiplying the main CR clock by a PLL
multiplication rate.
Subclock mode The machine clock is generated by dividing the subclock by two.
Sub-CR clock mode The machine clock is generated by dividing the sub-CR clock by two.