micro usb标准

Introduction
1.1 General
USB has become a popular interface for exchanging data between cell phone and portable devices. Many
of these devices have become so small it is impossible to use standard USB components as defined in the
USB 2.0 specification. In addition the durability requirements of the Cell Phone and Portable Devices
market exceed the specifications of the current interconnects. Since Cell Phones and other small Portable
Devices are the largest market potential for USB, this specification is addressing this very large market
while meeting all the requirements for electrical performance within the USB 2.0 specification.
1.2 Objective of the Specification
The purpose of this document is to define the requirements and features of a Micro-USB connector that will
meet the current and future needs of the Cell Phone and Portable Devices markets, while conforming to the
USB 2.0 specification for performance, physical size and shape of the Micro-USB interconnect.
This is not a stand-alone document. Any aspects of USB that are not specifically changed by this
specification are governed by the USB 2.0 Specification and USB On-The-Go Supplement.
1.3 Intended Audience/Scope
Cell phone and Portable Devices have become so thin that the current Mini-USB does not fit well within the
constraints of future designs. Additional requirements for a more rugged connector that will have durability
past 10,000 cycles and still meet the USB 2.0 specification for mechanical and electrical performance was
also a consideration. The Mini-USB could not be modified and remain backward compatible to the existing
connector as defined in the USB OTG specification.
1.4 Related Documents
USB 2.0
USB OTG Supplement