资料介绍
Reducing power consumption is always desirable in
systems where resources may be limited. This is
particularly true in USB systems, where designers must
not only understand the rules imposed by the USB
specification, but know when and how to use which of
the available power-saving features.
This application note discusses ways to manage power
on the members of the PIC18 family of microcontrollers
with nanoWatt technology in USB applications. In this
document, we will present a summary of the USB
specification in regards to power management and dis-
tribution and to describe when and how to use
power-saving features in response to different USB
events. We will also discuss how the advanced
power-saving features of enhanced PIC18 devices with
nanoWatt technology can be used to meet these goals.
Our focus in this document is on PIC18 devices
with the USB peripheral and uses the
PIC18F2455/2550/4455/4550 family of micro-
controllers as an example. All references to the device
data sheet in this document refer to the data sheet for
this family (DS39632). AN950
Power Management for PIC18 USB Microcontrollers
with nanoWatt Technology
Author: Rawin Rojvanit This discussion is limited to USB devices only and is not
intended for a USB host. The author assumes that the
Microchip Technology Inc.
readers have some basic knowledge about the USB
standard. All references to the USB specification in this
INTRODUCTION document refer to “USB Specification
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