Connecting the world

Through thick and thin

By Philippa Martin-King

Connectors play a vital role in any device. Yet they rarely attract much attention because the focus is generally on the device itself, be it a computer, telephone, photovoltaic module, or life-saving machine in a hospital. Connectors are simply expected to enable the effortless operation of the system in which they are installed. They are inconspicuous, yet must be both easy to access and to handle.

USB is used increasingly to charge devices USB is used increasingly to charge devices

When the weakest element becomes the strongest

Traditionally a connector has often been the weakest point of any installation, since over and above the electrotechnical role it plays in connecting and transmitting electricity from one source to another, it has to put up with being pulled, pushed and twisted. It often suffers unusually rough treatment in its everyday use. As a result, designers of connectors have come up with some ingenious approaches to ensure that their system will withstand harsh treatment and last as long as the appliance itself or at least have a very long life.

Worldwide adoption of USB

The most popular and successful connector in the world is the USB (universal serial bus) device. According to ElectronicsWeekly, there are over 6 billion units installed worldwide with an adoption rate of virtually 100 % in PCs and peripherals. High-speed USB 2.0 running at 480Mbit/s meets many needs of consumers. Yet the rising demand for high-definition video and faster downloading of digital-media files has led to the creation of SuperSpeed USB 3.0.

USB connectors have been purposely designed to be robust. While many previous connector designs were fragile, with pins that were so delicate that they would easily bend or break, the USB connector was designed from the outset to withstand much more wear and tear. The electrical contacts in a USB connector are protected by an adjacent plastic tongue, and the entire connecting assembly is usually enclosed in a protective metal sheath. USB was originally a way of connecting PCs to peripherals, and OTG (on-the-go) was invented for situations when two devices, neither of which was a PC, needed to be connected together – for example, a camera and a printer.

Use extended to charging

Now, the use of USB connectors has been extended. One example is to act as battery charging devices – connecting battery-powered products to the USB port of a computer, for example.

IEC TC (Technical Committee) 100 has several ongoing projects that cover various possible device interfaces based on USB connectors.

One of the aims of TC 100 has been to standardize a universal power adapter and charger solution for mobile terminals and other ICT (information and communication technology) devices. This will enable interoperability between a common EPS (external power supply) and a data-enabled mobile telephone. At present, this is one of the solutions adopted globally by manufacturers in an effort to reduce waste and to create a single standard battery-charging solution for mobile phone manufacturers. In creating a common EPS, EU consumers are able to re-use the same single external power supply with a variety of phones made by different manufacturers.

The resulting economies of scale imply fewer external power supplies will need to be manufactured and supplied with every phone sold. Lower production quantities mean less raw material is used. Shipping costs are lower, warehouse storage space is reduced and there are fewer chargers that need to be disposed of at the end of the phone’s useful life. It's an entirely win-win situation, not only for the consumer and the manufacturer, but for the environment too.

In January 2011, IEC TC 100, in collaboration with GSMA (the GSM Association that represents the interests of the worldwide mobile communications industry), announced IEC 62684, Interoperability specifications of common external power supply (EPS) for use with data-enabled mobile telephones.

Micro USB plug specifications

At the heart of the standard are the micro USB plug specifications issued by the USB-IF (Implementers Forum), with which the IEC has signed an MoU (Memorandum of Understanding).

In March 2011, TA (Technical Area) 1 produced the International Standard IEC 62637-1, Battery charging interface for small handheld multimedia devices - Part 1: 2 mm barrel interface, and IEC 62637-2, Battery charging interface for small handheld multimedia devices - Part 2: 2 mm barrel type interface conformance testing.

Barrel type battery charging interfaces are, as the name suggests, cylindrical. They have the advantage of being much lighter than transformer-based chargers and typically are used within the OMTP (open mobile terminal platform) for charging systems such as mobile phones. Gradually their use has become more widespread and they are increasingly popular. Today, there is a tremendous market of mobile devices, from cameras and telephones to tablets and homing devices. Systems can be recharged or connected simply using a standard USB plug on one end of a cable with a micro- or mini-USB or barrel plug on the other. One end connects to the computer or power adapter, the other, to the mobile terminal.

TA 14 works on device interfaces and methods of measurement for personal computing equipment. One of its PTs is working on another International Standard, IEC 62680, Battery charging interface for small hand held multimedia devices - Part 3: Micro USB battery charging interface.

At the end of October, IEC SC 48B: Connectors, a Subcommittee of TC 48: Electromechanical components and mechanical structures for electronic equipment, announced a pre-release version of the International Standard IEC 60511-1-100, Connectors for electronic equipment – Tests and measurements – Part 1-100: General – Applicable publications. Now at FDIS (Final Draft International Standard) stage, it is available for sale during the voting period. The new edition of the publication provides a listing of the 60512 series for carrying out specific tests on connectors. It particularly addresses new technical developments such as lead-free soldering which operates at different temperatures and is being used in a move towards more environmentally-friendly manufacturing.

USB is used increasingly to charge devices USB is used increasingly to charge devices
Barrel type interface is 2 mm Barrel type interface is 2 mm
Source: Digital Photography Review. Source: Digital Photography Review.