mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 119

• Manufacturer Part Number: mc9s12xd256
• Description: Hcs12x Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 3
Pierce Oscillator (S12XOSCLCPV1)
3.1
The Pierce oscillator (XOSC) module provides a robust, low-noise and low-power clock source. The
module will be operated from the V
of external components. It is designed for optimal start-up margin with typical crystal oscillators.
3.1.1
The XOSC will contain circuitry to dynamically control current gain in the output amplitude. This ensures
a signal with low harmonic distortion, low power and good noise immunity.
3.1.2
Two modes of operation exist:
Freescale Semiconductor
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1. Loop controlled Pierce oscillator
2. External square wave mode featuring also full swing Pierce without internal feedback resistor
High noise immunity due to input hysteresis
Low RF emissions with peak-to-peak swing limited dynamically
Transconductance (gm) sized for optimum start-up margin for typical oscillators
Dynamic gain control eliminates the need for external current limiting resistor
Integrated resistor eliminates the need for external bias resistor
Low power consumption:
— Operates from 2.5 V (nominal) supply
— Amplitude control limits power
Clock monitor
Introduction
Features
Modes of Operation
MC9S12XDP512 Data Sheet, Rev. 2.17
DDPLL
supply rail (2.5 V nominal) and require the minimum number
119