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:
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•
•
•
•
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.
PS024705-0405
P R E L I M I N A R Y
Oscillator Control
ZILOG [ ZILOG, INC. ]
