Datasheet

Chapter 11 Internal Clock Source (S08ICSV2)
MC9S08SH32 Series Data Sheet, Rev. 2
Freescale Semiconductor 171
11.1.2 Features
Key features of the ICS module follow. For device specific information, refer to the ICS Characteristics in
the Electricals section of the documentation.
• Frequency-locked loop (FLL) is trimmable for accuracy
— 0.1% resolution using internal 32kHz reference and 9-bit TRIM:FTRIM
— 2% deviation over voltage and temperature using internal 32kHz reference
• Internal or external reference clocks up to 5MHz can be used to control the FLL
— 3 bit select for reference divider is provided
• 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
– BDC clock is provided as a constant divide by 2 of the DCO output
• 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
11.1.3 Block Diagram
Figure 11-2 is the ICS block diagram.
PRELIMINARY