ZUSBOPTSC01ZAC datasheet(261/402 Pages) ZILOG

261 / 402 page

PS024604-1005

P R E L I M I N A R Y

Operation

Z8FMC16100 Series Flash MCU

Product Specification

239

Internal Precision Oscillator

The Internal Precision Oscillator (IPO) is designed for use without external components.

The IPO comes factory trimmed a ±4% frequency accuracy over the operating tempera-

ture and supply voltage range of the device. IPO features include:

• On-chip RC oscillator that does not require external components

• Trimmed to ±4% accuracy

• Target output frequency of 5.5296MHz

• Trimming possible through Flash option bits with user override

• Can eliminate crystals or ceramic resonators in applications where high timing accura-

cy is not required.

Operation

The internal oscillator is an RC relaxation oscillator that has had its sensitivity to power

supply variation minimized. By using ratio tracking thresholds, the effect of power supply

voltage is cancelled out. The dominant source of oscillator error is the absolute variance of

chip-level fabricated components, such as capacitors. Two 8-bit trimming registers, incor-

porated into the design, allow compensation of absolute variation of oscillator frequency.

Once calibrated, the oscillator frequency is relatively stable and does not require subse-

quent calibration.

By default, the oscillator is configured through the Flash Option bits. However, the user

code can override these trim values as described in Trim Option Bits section on page 223.

ZUSBOPTSC01ZAC 数据表(PDF) 261 Page - Zilog, Inc.