Charge your mobile devices from shutdown PCs
Do you have a drawer full of chargers somewhere that have outlasted whatever devices they were designed to charge? GSMA has estimated that manufacturers produce 51,000 metric tons of redundant chargers each year. To minimize the waste, IEC in 2011 announced the publication of a globally relevant universal phone-charger standard for data-enabled mobile telephones. According to the IEC, adoption of the standard “may also positively impact end-consumer prices and will reduce the overall CO2 footprint of this industry, potentially cutting greenhouse gas emissions by 13.6 million [metric tons] per year.”
Building on the IEC standard, STMicroelectronics has added features to its latest PC USB chips that could further reduce the environmental impact of charging mobile devices.
According to ST, “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…. 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.”
The chips (called charger emulators) employ a patented attach-detection feature, which operates when the PC is shut down, enabling the PC’s power supply to be activated for charging. The chips also monitor current to turn the power supply off when charging is complete, further maximizing energy savings. ST says other charger emulators require the PC to be in working or sleep mode to charge the device, which consumes more power than when the PC is in shutdown mode. The company says that when the USB port is active and waiting for a device to be connected, ST’s chips consume only one-sixteenth the power of other charger emulators. Both chips have circuitry to avoid discharging the PC’s battery when the PC is not plugged in.
The STCC5011 has a 1-A charge-current limit suitable for Apple iPod and iPhone devices. The STCC5021 has a limit of 2 A for charging iPad as well as iPod and iPhone devices. Both chips are compatible with the USB battery charging standard BC1.2, USB2.0, USB3.0, and Chinese telecommunications standard YD/T 1591-2009, which mandates use of USB charging to reduce electronic waste and protect the environment.
It sounds like a good idea, with a couple of caveats. Many mobile devices now synchronize wirelessly, making it unnecessary to establish a wired connection for data exchange. And second, I might want to take my phone but not my laptop for a short trip, in which case I would need to take a dedicated mobile device charger. Nevertheless, the ST chips offer a nice alternative.