Mixed-signal and power management chip vendor Dialog Semiconductor plc has developed an ac/dc interface adapter IC suitable for Quick Charge 2.0 power supplies. The ICs produced by Dialog enable up 88 percent conversion efficiency and support charger supplies of up to 40W.
Quick Charge is a proprietary standard developed by Qualcomm Inc. for charging smartphones, tablet computers and other mobile devices that operates up to 75 percent faster than conventional charging over a USB connection.
Dialog has two chips to support Quick Charge 2.0 that have come as a result of the company's acquisition of iWatt Inc. in July 2013 for approximately $310 million. Whereas Dialog's power management expertise had been in dc/dc conversion, the acquisition of iWatt gave the company an entry into ac/dc power conversion and power management for the solid-state lighting sector.
The iW620 and iW760 are fruit of that acquisition. The iW620 rapid charge interface IC resides on the secondary side of the AC/DC charger power supply and works with the iW760 primary-side digital pulse width modulation (PWM) controller. The iW620 detects commands from the Quick Charge 2.0 enabled mobile device via the USB cable and then communicates to the iW760 PWM primary-side controller to configure the adapter output voltage for the quickest charging regime. The iW620 ensures safe operation with a fast output voltage discharge from 9V or 12V down to 5V. Current sensing is performed by the iW1760 on the primary side, eliminating the need for a secondary-side current sense resistor; a more efficient solution than competing Quick Charge 2.0 wall charger approaches, Dialog claimed.
The chipset can produce 83 percent efficiency of conversion without a synchronous rectifier or 88 percent with one. And improved efficiency means that adapters can be made smaller without seeing heating problems.
"Reducing battery charge time is one of the most compelling trends today in smartphones," said Mark Tyndall, senior vice president of corporate development and strategy and general manager of the power conversion business group at Dialog, in a statement.
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