USB 2.0规范

USB 2.0 Specification Engineering Change Notice (ECN) #1: Mini-B connector
Date: 10/20/2000
Reason for ECN:
The USB 2.0 specified device-side connector – the B connector – is too large for use with
a new generation of handheld and mobile devices, e.g., cell phones which would benefit
from connectivity to the PC. This ECN incorporates a specification of a device-side mini
connector (hereafter referred to as a mini-B connector). The new connector only applies
to upstream facing ports, i.e., connectors on devices.
Summary of ECN:
The bulk of the ECN specifies the mechanical requirements for the mini-B plug,
receptacle and cable assembly. It also identifies the usage scope of this connector. The
last part of the ECN describes the minimum test criteria and performance requirements
for the new connector.
Benefits of ECN:
The ECN enables standardization of miniature device-side USB connectors and
consequent economies of scales and lower cost for a new and growing class of devices
which will benefit from connectivity to the PC. The standardization also allows
leveraging of the compliance test and certification model which is already in place for
USB connectors.
Assessment of Impact on Current Specification and Current USB Products:
The connector specified in the ECN will not have any impact on hardware or software of
existing USB products. The current USB spec already allows for vendor-specific device
side connectors – such cable assemblies are called captive assemblies. All that the ECN
does is to identify one such connector for use in devices which need the smaller size of
connector. There is a potential for some end-user confusion because of two standard
cable options; but this can be mitigated by appropriate end-user education.
Structure of ECN:
The ECN is in the form of a new Chapter 6 with the mini-B connector requirements
inserted into the appropriate locations. This format enables specification of the new
connector in context.