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USB chip enables charging from shutdown PCs

Posted: 29 Jul 2013 ?? ?Print Version ?Bookmark and Share

Keywords:PCs? charger emulator? USB charging?

STMicroelectronics has announced a pair of USB chips that claim to save energy and cut 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 STCC5011 and STCC5021 (called charger emulators) can detect when a mobile device has been connected. This enables the PC's power supply to be activated for charging.

The chips monitor current to turn the power supply off when charging is complete and thereby maximise the energy savings. 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.

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, boasted ST. 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.

The STCC5011 has a 1A charge-current limit geared for Apple iPod and iPhone. The STCC5021 has a limit of 2A for charging iPad as well as iPod and iPhone. 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. They also support proprietary chargers such as BlackBerry charging mode, as well as Apple divider mode (for 1A and 2A charging).

The STCC5011/5021 feature pin-selectable charger-emulation profiles, USB2.0-compliant USB data switch with 1000MHz bandwidth, low-resistance (60m?) integrated power switch, built-in safety protection, and charging-indication output in dedicated charging port (DCP) and Charging Downstream Port (CDP) modes, detailed the company.

Operation in PC advanced configuration & power interface (ACPI) modes allows support for remote wakeup in ACPI S3 mode (PC sleep mode) and device attachment detection in ACPI G2 mode (shutdown/soft-off, or S5).

The STCC5011 and STCC5021 are available in the VFQFPN 16-pin 3 x 3 x 0.8mm package, priced from $0.75 for orders over 1,000 pieces.

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