MC908JB16DWE Datasheet, PDF (93/332 Pages) Freescale Semiconductor, Inc – Microcontrollers

Technical Data — MC68HC908JB16
Section 7. Oscillator (OSC)
7.1 Contents
7.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
7.3 Oscillator External Connections . . . . . . . . . . . . . . . . . . . . . . . .94
7.4 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
7.4.1 Crystal Amplifier Input Pin (OSC1). . . . . . . . . . . . . . . . . . . . 95
7.4.2 Crystal Amplifier Output Pin (OSC1) . . . . . . . . . . . . . . . . . . 95
7.4.3 Oscillator Enable Signal (SIMOSCEN). . . . . . . . . . . . . . . . . 95
7.4.4 Crystal Output Frequency Signal (OSCXCLK). . . . . . . . . . . 95
7.4.5 Clock Doubler Out (OSCDCLK) . . . . . . . . . . . . . . . . . . . . . . 95
7.4.6 Oscillator Out (OSCOUT). . . . . . . . . . . . . . . . . . . . . . . . . . . 96
7.5 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
7.5.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96
7.5.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96
7.6 Oscillator During Break Mode. . . . . . . . . . . . . . . . . . . . . . . . . . 96
7.2 Introduction
The oscillator circuit is designed for use with crystals or ceramic
resonators. The oscillator circuit generates the crystal clock signal,
OSCXCLK, and passes through a clock doubler to produce OSCDCLK.
This clock doubler clock is further divided by two before being passed on
to the system integration module (SIM) for bus clock generation.
Figure 7-1 shows the structure of the oscillator. The oscillator requires
various external components.
The MC68HC908JB16 operates from a nominal 12MHz crystal,
providing a 6MHz internal bus clock. The 12MHz clock is required for
various modules, such as the CGMs and USB. The clock doubler clock,
OSCDCLK, is used as the base clock for the COP module.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Oscillator (OSC)
Technical Data
93