MC68HC908KX8 Datasheet, PDF (100/310 Pages) Motorola, Inc – Microcontrollers

Internal Clock Generator Module (ICG)
7.5.6
7.5.6.1
7.5.6.2
7.5.6.3
7.5.7
Nominal Frequency Settling Time . . . . . . . . . . . . . . . . . . . 122
Settling to Within 15 Percent . . . . . . . . . . . . . . . . . . . . . 123
Settling to Within 5 Percent . . . . . . . . . . . . . . . . . . . . . . 123
Total Settling Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Trimming Frequency on the Internal Clock Generator . . . . 125
7.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
7.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126
7.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126
7.7 CONFIG or MOR Options. . . . . . . . . . . . . . . . . . . . . . . . . . . .127
7.7.1 External Clock Enable (EXTCLKEN) . . . . . . . . . . . . . . . . . 127
7.7.2 External Crystal Enable (EXTXTALEN) . . . . . . . . . . . . . . . 127
7.7.3 Slow External Clock (EXTSLOW) . . . . . . . . . . . . . . . . . . . 128
7.7.4 Oscillator Enable In Stop (OSCENINSTOP) . . . . . . . . . . . 128
7.8 Input/Output (I/O) Registers . . . . . . . . . . . . . . . . . . . . . . . . . . 129
7.8.1 ICG Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
7.8.2 ICG Multiplier Register . . . . . . . . . . . . . . . . . . . . . . . . . . . .133
7.8.3 ICG Trim Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
7.8.4 ICG DCO Divider Register . . . . . . . . . . . . . . . . . . . . . . . . . 134
7.8.5 ICG DCO Stage Register . . . . . . . . . . . . . . . . . . . . . . . . . . 135
7.2 Introduction
The internal clock generator module (ICG) is used to create a stable
clock source for the microcontroller without using any external
components. The ICG generates the oscillator output clock
(CGMXCLK), which is used by the computer operating properly (COP),
low-voltage inhibit (LVI), and other modules. The ICG also generates the
clock generator output (CGMOUT), which is fed to the system
integration module (SIM) to create the bus clocks. The bus frequency will
be one-fourth the frequency of CGMXCLK and one-half the frequency of
CGMOUT. Finally, the ICG generates the timebase clock (TBMCLK),
which is used in the timebase module (TBM).
Technical Data
100
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 — Rev. 1.0
Internal Clock Generator Module (ICG)
MOTOROLA