Charging Mobile Devices from Shut Down PCs Becomes Reality with Unique USB Chips from STMicroelectronics

STMicroelectronics has perfected advanced features in its latest PC USB chips chips that significantly reduce the environmental impact of charging mobile devices.

As smartphones and media players typically connect to a PC for data exchange, users are tending also to charge their devices from PC USB ports. Indeed, the International Electrotechnical Commission’s (IEC) universal phone-charger standard promotes USB charging by making use of the USB interface specification. The IEC said the standard could help reduce the 51,000 tons of redundant chargers produced each year and cut the mobile industry’s annual greenhouse gas emissions by 13.6 million tons.

ST’s new STCC5011 and STCC5021 go a step further in saving energy and reducing CO2 emissions by allowing users to charge mobile devices from a USB port even when the computer is in software-controlled shutdown mode. Using a unique attach-detection feature, which is patented by ST and operates when the PC is shut down, the chips (called charger emulators) can detect when a mobile device has been connected. This enables the PC’s power supply to be activated for charging.

Charging in PC shutdown mode with the STCC5011 or STCC5021 improves the energy efficiency of USB charging and makes it more convenient for end users. Moreover, when the USB port is active and waiting for a device to be connected for charging, ST’s chips consume only 1/16 of the power of other charger emulators. This allows PCs to offer convenient USB charging with minimal impact on power consumption or PC battery life during normal use. Both chips have circuitry to avoid discharging the PC’s battery, which allows even the most mobile of users to charge devices safely while using the PC on battery power alone.