Internal Clock Source (S08ICSV3)
MC9S08QE128 MCU Series Reference Manual, Rev. 2
Freescale Semiconductor 205
11.1.3 Features
Key features of the ICS module are:
• Frequency-locked loop (FLL) is trimmable for accuracy
• Internal or external reference clocks can be used to control the FLL
• Reference divider is provided for external clock
• Internal reference clock has 9 trim bits available
• Internal or external reference clocks can be selected as the clock source for the MCU
• Whichever clock is selected as the source can be divided down
— 2 bit select for clock divider is provided
– Allowable dividers are: 1, 2, 4, 8
• Control signals for a low power oscillator as the external reference clock are provided
— HGO, RANGE, EREFS, ERCLKEN, EREFSTEN
• FLL Engaged Internal mode is automatically selected out of reset
• BDC clock is provided as a constant divide by 2 of the low range DCO output
• Three selectable digitally controlled oscillators (DCO) optimized for different frequency ranges.
• Option to maximize output frequency for a 32768 Hz external reference clock source.
11.1.4 Block Diagram
Figure 11-2 is the ICS block diagram.
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