MC68HC908KX8 Datasheet, PDF (101/310 Pages) Motorola, Inc – Microcontrollers

Internal Clock Generator Module (ICG)
Features
7.3 Features
The ICG has these features:
• Selectable external clock generator, either 1-pin external source
or 2-pin crystal, multiplexed with port pins
• Internal clock generator with programmable frequency output in
integer multiples of a nominal frequency (307.2 kHz ± 25 percent)
• Frequency adjust (trim) register to improve variability
• Bus clock software selectable from either internal or external clock
(bus frequency range from 76.8 kHz ± 25 percent to 9.75 MHz ±
25 percent in 76.8-kHz increments
NOTE: For the MC68HC908KX8, do not exceed the maximum bus frequency of
8 MHz at 5.0 V and 4 MHz at 3.0 V.
• Timebase clock automatically selected from external if external
clock is available
• Clock monitor for both internal and external clocks
7.4 Functional Description
The ICG, shown in Figure 7-1, contains these major submodules:
• Clock enable circuit
• Internal clock generator
• External clock generator
• Clock monitor circuit
• Clock selection circuit
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 — Rev. 1.0
MOTOROLA
Internal Clock Generator Module (ICG)
Technical Data
101