The Universal Serial Bus (USB) is the most used computer interface in the world. It started as an expansion bus for personal computers, but has proliferated quickly due to its flexibility, performance, and hot plug capability. It is used by most portable electronic devices that require PC connectivity for file transfers. These devices include MP3 players, digital cameras, cellphones, and tablets. Since a standard USB bus downstream port can provide at least 500 mA of current, it was convenient to use it for charging these devices. This document describes how this current limit can be increased and how the SMSC USB2534 Hub Controller with RapidCharge™ can be used to implement a System solution to efficiently charge portable devices.
Unless stated otherwise, references to the USB2534 also apply to the following parts: USB2533,USB2532, USB4604, USB4624, USB3613, and USB3813.