Cost-cutting power control ICs address most critical reliability issue in white goods

Dialog Semiconductor has introduced two power control integrated circuits that address the most critical reliability issue in white goods while reducing manufacturers’ bills-of-materials (BOM) costs without compromising power supply performance. The household appliance market is growing at 3.8% annually and will reach 430 million units by 2017 (Market analyst, Freedonia Group, 2014). Dialog’s new digital controllers are designed for use in dishwashers, refrigerators, cooking ranges, microwaves and other high volume appliance applications. Most appliances today use secondary-side control to maintain the tight output voltage regulation for stable operation in multi-rail systems. For example, a 5V output for the system microcontroller (MCU) needs ±5% voltage accuracy, while 12V to 16V rails for motor or relay control require ±10% accuracy. However, secondary-side designs require optocouplers, which have significantly worse failure rates compared to other components in the power supply. The new iW1818 and iW1830 AccuSwitch pulse width modulation (PWM) controllers use Dialog’s PrimAccurate primary-side control to eliminate the need for optocouplers, the weakest link in achieving the high reliability and long operating lifetime for appliances. The elimination of a secondary-side regulator and optocoupler means reduced BOM costs and fewer solder joints for potential failure, inherently increasing reliability. Dialog’s patented intelligent digital control loop technology provides accurate voltage cross-regulation between the multiple power rails in the system, says the company. “The common notion is that primary-side regulation in white goods applications may eliminate the optocoupler, but comes at the expense of voltage cross-regulation accuracy,” explains Davin Lee, senior vice president and general manager, Power Conversion Business Group, Dialog Semiconductor. “Leveraging Dialog’s proven expertise in digital control, the iW1818 and iW1830 provide the best of both worlds – higher reliability of primary-side design and accurate cross regulation for lower cost, longer lifetime appliance designs.” The iW1818 and iW1830 simplify appliance power supply designs by integrating a high-voltage power switch (800V BJT and 700V MOSFET, respectively) and both support high capacitance loads (up to 6,000µF) at up to 12V. The adaptive multi-mode PWM/PFM control in the iW1818 and iW1830 dynamically changes the switching frequency to optimise the system for high efficiency even at light loads. They provide >80% active average efficiency, maintain high efficiency at loads as light as 10% and achieve <50mW no-load standby power with fast standby recovery time. This helps white goods designers meet global energy efficiency regulations, including the European Ecodesign Directive and the U.S. Department of Energy (DoE) energy conservation standards. Both parts come in a thermally-efficient, small-footprint, easy-to-use PDIP-7 package that ensures excellent thermal performance using a single-layer PC board. In addition to built-in over-temperature protection, they offer full protection from fault conditions, such as output short-circuit, over-voltage and over-current, says the company.