NXP Semiconductors MC9S08QL4, Reference Manual

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MC9S08QL8 MCU Series Reference Manual, Rev. 1
NXP Semiconductors 149
Chapter 11
Internal Clock Source (S08ICSV3)
11.1 Introduction
The internal clock source (ICS) module provides clock source choices for the MCU. The module contains
a frequency-locked loop (FLL) as a clock source that is controllable by either an internal or an external
reference clock. The module can provide this FLL clock or either of the internal or external reference
clocks as a source for the MCU system clock. There are also signals provided to control a low power
oscillator (XOSCVLP) module to allow the use of an external crystal/resonator as the external reference
clock.
Whichever clock source is chosen, it is passed through a reduced bus divider (BDIV) which allows a lower
final output clock frequency to be derived.
11.1.1 DCO Select bits
The ICS on the MC9S08QL8 series is configured to support only the low range DCO, therefore the DRS
and DRST bits in ICSSC have no effect.