The GSM Association, which organizes the Mobile World Congress and spans more than 220 countries, also announced intentions to standardize mobile phone charger connections with a USB connector. 5 Both the Korean Telecommunications Technology Association and Chinese Ministry of Industry and Information Technology have released technical requirements for the standardization of mobile phone charging. 6
Even the International Telecommunication Union, a specialized agency within the United Nations, published ITU-T L.1000, its recommendation to adopt a universal charger based on requirements from the GSMA, EU, and Chinese proposals. 7 With the updated power-delivery provisions added to USB2.0, the introduction of USB3.1 in 2013, and the new Type-C connector in 2014, the adoption of a standard connector will continue to be influenced heavily by USB standards.
Charger Detection and Ports in BC1.2
Why are standards committees and governing bodies choosing to standardize around USB connectors and the protocols outlined in BC1.2? Establishing a common standard allows interoperability, optimal performance, and safety among any devices using USB. The specification defines how much power can be supplied by any port, as well as a smart way for portable devices to detect how much power can be drawn. Thus, any portable equipment manufacturer can design their product to be compatible with as many USB ports as possible.
Manufacturers will know how best to utilize each USB port and can anticipate what voltages and currents will be applied by the USB port. Given this knowledge, they can design without the risk of electrical overstress. Finally, the increasing the amount of charging current that a device can use significantly reduces the total charge time required. Consequently, charger detection is an important feature that should be built into all rechargeable devices that incorporate a USB port.
Before discussing the charger detection protocol, it is important to know the differences among available USB ports. A downstream port supports USB 2.0 communication, and a