Dialog collaborates with Qualcomm to achieve higher efficiency rapid smartphone charging

January 20, 2014 // By Paul Buckley
Dialog Semiconductor plc has unveiled the company's high efficiency AC/DC adapter interface IC for Qualcomm Quick Charge 2.0 power supplies.

The new iW620 rapid charge interface IC resides on the secondary side of the AC/DC charger power supply and works with Dialog’s iW1760 PrimAccurateTM primary-side digital pulse width modulation (PWM) controller. Efficiency as high as 88% enables the higher power density needed for smaller form-factor fast charging adapters. Quick Charge 2.0 is a proprietary protocol from Qualcomm Technlogies, Inc., a wholly owned subsidiary of Qualcomm Incorporated (NASDAQ: QCOM), for charging smartphones, tablets and other mobile devices up to 75% faster than conventional USB charging technology.

Dialog’s Quick Charge 2.0 rapid charge AC/DC adapter solution delivers high efficiency up to 83% without the need for a synchronous rectifier as required by competing solutions. For the ultimate in high power density and small form factor, Dialog’s Quick Charge 2.0 rapid charge solution can be used with a synchronous rectifier to provide even higher efficiency up to 88%.

The iW620 rapid charge interface IC detects commands from the Quick Charge 2.0-enabled mobile device via the USB cable, then communicates with the iW1760 PWM primary-side controller and configures the power adapter output voltage.

Current sensing is performed by the iW1760 on the primary side, eliminating the need for a secondary-side current sense resistor for an inherently more efficient solution than competing Quick Charge 2.0 wall charger approaches. Primary-side current control also enables low cost implementation of different constant current thresholds for each output voltage.

The iW620 ensures safe operation with programmable, patented active fast output voltage discharge from 9 V or 12 V down to 5 V. So, when the USB cable is unplugged from a Quick Charge 2.0 phone and then used with a non-Quick Charge 2.0 phone, the iW620 rapidly discharges the output voltage down to 5V, to protect the phone from damage.

The iW620 supports Quick Charge 2.0 High Voltage Dedicated Charging Port (HVDCP) Class A (5 V, 9 V, 12 V output) applications and, with the iW1760 primary-side digital PWM