Rapid charge controller supports MediaTek fast charge protocol
Dialog’s iW1680 is a single-chip solution, which is being demonstrated at the Mobile World Congress 2014 in Barcelona, uses the Dialog’s intelligent rapid charge digital algorithm and digital primary-side control technology to reduce charge times in USB AC/DC wall chargers with no bill of materials (BOM) cost premium compared with slower conventional charging technologies.
Conventional USB chargers provide a fixed 5 V supply that requires a buck converter inside the handset to convert the 5 V down to the required output voltage. The iW1680 uses Dialog’s built-in, intelligent rapid charge digital algorithm that communicates with MediaTek Pump Express-compatible phones and dynamically scales the output voltage of the wall charger to deliver the optimized level required by the phone at any given time. The overall system cost is lowered by eliminating the need for an input buck converter in the phone and reduces charge times by enabling more efficient power transfer to the phone battery.
Building on Dialog’s leadership in accurate primary-side control for AC/DC power supplies with the latest derivative of its PrimAccurate primary-side controller platform, the iW1680 rapid charge AC/DC controller embeds digital analysis on the primary side of the isolated power supply within the charger. The result is that voltage scaling can be achieved without the need for any intelligence on the secondary side and provides further cost reductions. The device is ideal for use in compact AC/DC chargers/adapters for portable electronics and supports fast charge enabled adapters for smartphones. The iW1680 is also suitable as a linear AC/DC replacement.
The iW1680 supports power adapters up to 7.5 W, with high active average efficiency and low no-load power consumption less than 30 mW. Communication between the phone and iW1680 is through the VBUS supply line. Voltage scaling is digitally managed on the primary side of the transformer in the AC/DC adapter by the iW1680, which analyses the signal of the VBUS and scales its output voltage accordingly. The iW1680 easily and efficiently drives low-cost bipolar junction transistor (BJT) switches to further drive down BOM costs and reduce electromagnetic interference (EMI).
The iW1680 comes in a 6-pin SOT23 package. Full protection features include built-in output short-circuit, and output overvoltage, output over-current and over-temperature protection.
The launch of the iW1680 means that Dialog is now supporting rapid charge solutions from the two major phone systems vendors in the world – Qualcomm and Mediatek.
Last month Dialog announced the launch of another rapid charge interface chip that is compatible with the Qualcomm Quick Charge 2.0 rapid charge AC/DC adapter solution which was revealed at MWC 2013. Quick Charge 2.0 is a proprietary protocol from Qualcomm Technlogies, Inc., for charging smartphones, tablets and other mobile devices up to 75% faster than conventional USB charging technology.
The iW620 rapid charge interface IC resides on the secondary side of the AC/DC charger power supply and works with Dialog’s iW1760 PrimAccurate primary-side digital pulse width modulation (PWM) controller. 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%.
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