s908ab32ag0cfue Freescale Semiconductor, Inc, s908ab32ag0cfue Datasheet - Page 132

• Manufacturer Part Number: s908ab32ag0cfue
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Clock Generator Module (CGM)
9.2 Introduction
9.3 Features
Technical Data
132
9.8.1
9.8.2
9.9
9.10
9.10.1
9.10.2
9.10.3
9.10.4
This section describes the clock generator module (CGM). The CGM
generates the crystal clock signal, CGMXCLK, which operates at the
frequency of the crystal. The CGM also generates the base clock signal,
CGMOUT, from which the system integration module (SIM) derives the
system clocks. CGMOUT is based on either the crystal clock divided by
two or the phase-locked loop (PLL) clock, CGMVCLK, divided by two.
The PLL is a frequency generator designed for use with 1MHz to 8MHz
crystals or ceramic resonators. The PLL can generate an 8MHz bus
frequency without using a higher frequency crystal.
Features of the CGM include the following:
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•
•
•
•
Phase-locked loop with output frequency in integer multiples of the
crystal reference
Programmable hardware voltage-controlled oscillator (VCO) for
low-jitter operation
Automatic bandwidth control mode for low-jitter operation
Automatic frequency lock detector
CPU interrupt on entry or exit from locked condition
CGM During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . 151
Acquisition/Lock Time Specifications . . . . . . . . . . . . . . . . . . . 151
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151
Acquisition/Lock Time Definitions. . . . . . . . . . . . . . . . . . . .152
Parametric Influences On Reaction Time. . . . . . . . . . . . . . 153
Choosing a Filter Capacitor . . . . . . . . . . . . . . . . . . . . . . . . 154
Reaction Time Calculation . . . . . . . . . . . . . . . . . . . . . . . . . 155
Clock Generator Module (CGM)
MC68HC908AB32
Freescale Semiconductor
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Rev. 1.1