AN006 Datasheet, PDF (1/8 Pages) Analog Intergrations Corporation – USB Protections

AN006
Advanced Solutions for USB Protections
Abstract
The AIC1526 is a dual high-side power switch for
self-powered and bus-powered USB applications.
This application note describes how the AIC1526
provides the power switching and over-current
protection. The items such as bus-powered hubs
and self-powered hubs are first introduced, after
which, the power distribution of USB specification
(version 1.0) and the key points of AIC1526
application will be followed.
Introduction
The universal serial bus (USB) interface is a 12
Mb/s, multiplexed serial bus designed for low to
medium speed PC peripherals. The USB interface
consists of four lines (see Figure 1). Two data
lines(D+,D-) are used for differential data
transmission and the other two power lines are for
power distribution of the 5 volts. The USB
interface is conceived for hot-plug-unplug of
peripheral devices to achieve the real
“plug-and-play” function.
•2 power lines:
-- 5V
-- GND
•2 data lines
-- D+
-- D-
5V
D+
D-
GND
Figure 1. USB Connector
Hubs provide distributions of data and power to
downstream (away from the host) devices and
communicate with the host. A hub consists of one
upstream port and several downstream ports (see
Figure 2). By connecting the serial connecting
hubs, the number of devices can be increased up
to the maximum of 127 devices.
May 1998
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