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Monday, July 29, 2013
 Charging Mobile Devices from Shutdown PCs
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Message Text: 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.

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 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. The chips also monitor current to turn the power supply off when charging is complete and thereby maximize 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. 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 suitable 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, as described above).

Major features of STCC5011/5021:

- Pin-selectable charger-emulation profiles
- USB2.0-compliant USB data switch with 1000MHz bandwidth
- Low-resistance (60mΩ) integrated power switch
- Built-in safety protection
- Charging-indication output in DCP (Dedicated Charging Port) and CDP (Charging Downstream Port) modes

Operation in PC Advanced Configuration & Power Interface (ACPI) modes:

- Support for remote wakeup in ACPI S3 mode (PC sleep mode)
- Device attachment detection in ACPI G2 mode (shutdown/soft-off, or S5)

The STCC5011 and STCC5021 are in production now, 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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