BS EN 62680-3:2013 Universal serial bus interfaces for data and power. USB battery charging specification, Revision 1.2

What is BS EN 62680-3 – Specification for USB battery charging about? 
BS EN 62680-3 series discusses standards for universal serial bus interfaces for data and power. 
BS EN 62680-3 is the third part of the multiple series that focuses on the Battery Charging Working Group is chartered with creating specifications that define limits as well as detection, control and reporting mechanisms to permit devices to draw current in excess of the USB 2.0 specification for charging and/or powering up from dedicated chargers, hosts, hubs and charging downstream ports. These mechanisms are backwards compatible with USB 2.0 compliant hosts and peripherals. 
Who is BS EN 62680-3 - Specification for USB battery charging for? 
BS EN 62680-3 on micro-USB cables and connectors is useful for: 
IT firms/software engineers 
IT automation industries 
USB technology operators 
Hardware manufacturers 
USB device manufacturers 
Hardware/software engineers 
Product development teams 
Why should you use BS EN 62680-3 - Specification for USB battery charging? 
The USB ports on personal computers are convenient places for Portable Devices (PDs) to draw current for charging their batteries. This convenience has led to the creation of USB Chargers that simply expose a USB standard-A receptacle. This allows PDs to use the same USB cable to charge from either a PC or a USB Charger. 
BS EN 62680-3 assists you with the USB 2.0 specification requirement that after connecting, a PD must draw less than: 
2.5 mA average, if the bus is suspended 
100 mA, if a bus is not suspended and not configured 
500 mA, if a bus is not suspended and configured for 500 mA 
In short, BS EN 62680-3 specifies PD procedures for determining how much current it is permitted to draw from an upstream USB port, as well as techniques for distinguishing between a Standard Downstream Port and a Charging Port. BS EN 62680-3 specifies the requirements for a compliant USB charger, which is referred to as a USB Charger in this specification.