MC68HC708AS48 FREESCALE [Freescale Semiconductor, Inc], MC68HC708AS48 Datasheet - Page 98

• Manufacturer Part Number: MC68HC708AS48
• Description: Advance Information
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Clock Generator Module (CGM)
8.2 Introduction
8.3 Features
Advance Information
98
8.8
8.8.1
8.8.2
8.9
8.10
8.10.1
8.10.2
8.10.3
8.10.4
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 1-MHz to
16-MHz crystals or ceramic resonators. The PLL can generate an 8-MHz
bus frequency without using a 32-MHz crystal.
Features of the CGM include:
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•
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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
Special Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .118
CGM During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . .119
Acquisition/Lock Time Specifications . . . . . . . . . . . . . . . . . . .119
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .118
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .118
Acquisition/Lock Time Definitions . . . . . . . . . . . . . . . . . . .119
Parametric Influences on Reaction Time . . . . . . . . . . . . .121
Choosing a Filter Capacitor. . . . . . . . . . . . . . . . . . . . . . . .122
Reaction Time Calculation . . . . . . . . . . . . . . . . . . . . . . . .123
Clock Generator Module (CGM)
MC68HC708AS48
MOTOROLA
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Rev. 4.0