Àû²©¡¤(¼¯ÍÅ)ÓÐÏÞ¹«Ë¾¹ÙÍø

DEVICE OVERVIEW

This document contains device specific information for the following devices: This family offers the advantages of all PIC18 micro controllers ¨C namely, high computational performance at an economical price ¨C with the addition of high endurance, Enhanced Flash program memory. On top of these features, the PIC18F4321 family introduces design enhancements that make these microcontrollers a logical choice for many high-performance, power sensitive applications.

? PIC18F2221 ? PIC18LF2221

? PIC18F2321 ? PIC18LF2321

? PIC18F4221 ? PIC18LF4221

? PIC18F4321 ? PIC18LF4321

New Core Features

nanoWatt TECHNOLOGY

All of the devices in the PIC18F4321 family incorporate a range of features that can significantly reduce power consumption during operation. Key items include:

? Alternate Run Modes:By clocking the controller from the Timer1 source or the internal oscillator

block, power consumption during code execution can be reduced by as much as 90%.

? Multiple Idle Modes:The controller can also run with its CPU core disabled but the peripherals still active. In these states, power consumption can be reduced even further, to as little as 4% of normal operation requirements.

? On-the-Fly Mode Switching:The power-managed modes are invoked by user code during operation, allowing the user to incorporate power-saving ideas into their application¡¯s software design.

? Low Consumption in Key Modules: The power requirements for both Timer1 and the Watchdog Timer are minimized. See Section 26.0 ¡°Electrical Characteristics¡± for values.

MULTIPLE OSCILLATOR OPTIONS AND FEATURES

All of the devices in the PIC18F4321 family offer ten different oscillator options, allowing users a wide range of choices in developing application hardware. These include:

? Four Crystal modes, using crystals or ceramic resonators.

? Two External Clock modes, offering the option of using two pins (oscillator input and a divide-by-4 clock output) or one pin (oscillator input, with the second pin reassigned as general I/O).

? Two External RC Oscillator modes with the same pin options as the External Clock modes.

? Two Internal Oscillator modes which provide an 8 MHz clock and an INTRC source

(approximately 31 kHz), as well as a range of 6 user-selectable clock frequencies, between

125 kHz to 4 MHz, for a total of 8 clock frequencies. One or both of the oscillator pins can be used for general purpose I/O.

? A Phase Lock Loop (PLL) frequency multiplier, available to both the high-speed crystal and

internal oscillator modes, which allows clock speeds of up to 40 MHz. Used with the internal

oscillator, the PLL gives users a complete selection of clock speeds, from 31 kHz to 32 MHz ¨C all

without using an external crystal or clock circuit. Besides its availability as a clock source, the internal oscillator block provides a stable reference source that gives the family additional features for robust operation:

? Fail-Safe Clock Monitor:This option constantly monitors the main clock source against a reference signal provided by the internal oscillator. If a clock failure occurs, the controller is switched to the internal oscillator block, allowing for continued low-speed operation or a safe application shutdown.

? Two-Speed Start-up:This option allows the internal oscillator to serve as the clock source

from Power-on Reset, or wake-up from Sleep mode, until the primary clock source is available.