Z8F082ASH020SC datasheet(178/244 Pages) ZILOG

178 / 244 page

PS024705-0405

P R E L I M I N A R Y

Oscillator Control

Z8 Encore! XP® F08xA Series

Product Specification

160

Oscillator Control

Overview

The Z8 Encore! XP® F08xA Series devices uses five possible clocking schemes, each

user-selectable:

• On-chip precision trimmed RC oscillator

• On-chip oscillator using off-chip crystal or resonator

• On-chip oscillator using external RC network

• External clock drive

• On-chip low precision Watch-Dog Timer oscillator

In addition, Z8 Encore! XP® F08xA Series devices contain clock failure detection and

recovery circuitry, allowing continued operation despite a failure of the primary oscillator.

Operation

This chapter discusses the logic used to select the system clock and handle primary oscil-

lator failures. A description of the specific operation of each oscillator is outlined else-

where in this document. The detailed description of the Watch-Dog Timer Oscillator starts

on page 79, the Internal Precision Oscillator description begins on page 169, and the chap-

ter outlining the Crystal Oscillator begins on page 165 of this document.

System Clock Selection

The oscillator control block selects from the available clocks. Table 101 details each clock

source and its usage.

Z8F082ASH020SC Datasheet(PDF) 178 Page - Zilog, Inc.