PIC18F2450/4450
1.1.3
MULTIPLE OSCILLATOR OPTIONS
AND FEATURES
1.0
DEVICE OVERVIEW
This document contains device-specific information for
the following devices:
All of the devices in the PIC18F2450/4450 family offer
twelve different oscillator options, allowing users a wide
range of choices in developing application hardware.
These include:
• PIC18F2450
This family of devices offers the advantages of all PIC18
microcontrollers namely, high computational
performance at an economical price – with the addition of
high endurance, Enhanced Flash program memory. In
addition to these features, the PIC18F2450/4450 family
introduces design enhancements that make these micro-
controllers a logical choice for many high-performance,
power sensitive applications.
• PIC18F4450
–
• Four Crystal modes using crystals or ceramic
resonators.
• Four 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).
• An INTRC source (approximately 31 kHz, stable
over temperature and VDD). This option frees an
oscillator pin for use as an additional general
purpose I/O.
1.1
New Core Features
1.1.1
nanoWatt TECHNOLOGY
• A Phase Lock Loop (PLL) frequency multiplier,
available to both the High-Speed Crystal and
External Oscillator modes, which allows a wide
range of clock speeds from 4 MHz to 48 MHz.
All of the devices in the PIC18F2450/4450 family
incorporate a range of features that can significantly
reduce power consumption during operation. Key
items include:
• Asynchronous dual clock operation, allowing the
USB module to run from a high-frequency
oscillator while the rest of the microcontroller is
clocked from an internal low-power oscillator.
• Alternate Run Modes: By clocking the controller
from the Timer1 source or the internal RC
oscillator, power consumption during code
execution can be reduced by as much as 90%.
The internal oscillator provides a stable reference
source that gives the family additional features for
robust operation:
• 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.
• 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, allowing for
continued low-speed operation or a safe
application shutdown.
• 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.
• 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.
• Low Consumption in Key Modules: The
power requirements for both Timer1 and the
Watchdog Timer are minimized. See
Section 21.0 “Electrical Characteristics” for
values.
1.1.2
UNIVERSAL SERIAL BUS (USB)
Devices in the PIC18F2450/4450 family incorporate a
fully featured Universal Serial Bus communications
module that is compliant with the USB Specification
Revision 2.0. The module supports both low-speed and
full-speed communication for all supported data
transfer types. It also incorporates its own on-chip
transceiver and 3.3V regulator and supports the use of
external transceivers and voltage regulators.
© 2006 Microchip Technology Inc.
Advance Information
DS39760A-page 7
MICROCHIP [ MICROCHIP ]
