M68HC08 datasheet(111/288 Pages) FREESCALE

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MC68HC908BD48 — Rev. 2.1

Data Sheet

Freescale Semiconductor

Oscillator (OSC)

111

Data Sheet — MC68HC908BD48

Section 8. Oscillator (OSC)

8.1 Contents

8.2

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

8.3

Oscillator External Connections . . . . . . . . . . . . . . . . . . . . . . . 112

8.4

I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

8.4.1

Crystal Amplifier Input Pin (OSC1). . . . . . . . . . . . . . . . . . . 113

8.4.2

Crystal Amplifier Output Pin (OSC2) . . . . . . . . . . . . . . . . . 113

8.4.3

Oscillator Enable Signal (SIMOSCEN). . . . . . . . . . . . . . . . 113

8.4.4

External Clock Source (OSCXCLK) . . . . . . . . . . . . . . . . . . 113

8.4.5

Oscillator Out (OSCOUT). . . . . . . . . . . . . . . . . . . . . . . . . . 113

8.5

Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

8.5.1

Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

8.5.2

Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

8.6

Oscillator During Break Mode. . . . . . . . . . . . . . . . . . . . . . . . . 114

8.2 Introduction

The oscillator circuit is designed for use with crystals or ceramic

resonators. The oscillator circuit generates the crystal clock signal,

OSCXCLK, at the frequency of the crystal. This signal is divided by two

before being passed on to the SIM for bus clock generation. Figure 8-1

shows the structure of the oscillator. The oscillator requires various

external components.

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