MC9S12Q128_10 Datasheet, PDF (343/644 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

Chapter 11
Oscillator (OSCV2) Block Description
11.1 Introduction
The OSCV2 module provides two alternative oscillator concepts:
• A low noise and low power Colpitts oscillator with amplitude limitation control (ALC)
• A robust full swing Pierce oscillator with the possibility to feed in an external square wave
11.1.1 Features
The Colpitts OSCV2 option provides the following features:
• Amplitude limitation control (ALC) loop:
— Low power consumption and low current induced RF emission
— Sinusoidal waveform with low RF emission
— Low crystal stress (an external damping resistor is not required)
— Normal and low amplitude mode for further reduction of power and emission
• An external biasing resistor is not required
The Pierce OSC option provides the following features:
• Wider high frequency operation range
• No DC voltage applied across the crystal
• Full rail-to-rail (2.5 V nominal) swing oscillation with low EM susceptibility
• Fast start up
Common features:
• Clock monitor (CM)
• Operation from the V_DDPLL 2.5 V (nominal) supply rail
11.1.2 Modes of Operation
Two modes of operation exist:
• Amplitude limitation controlled Colpitts oscillator mode suitable for power and emission critical
applications
• Full swing Pierce oscillator mode that can also be used to feed in an externally generated square
wave suitable for high frequency operation and harsh environments
Freescale Semiconductor
MC9S12Q128
343
Rev 1.10