Dialog's PWM controller IC lowers cost as well as standby power in smartphone supplies



Dialog Semiconductor, a provider of highly integrated power management, audio, AC/DC and short-range wireless technologies, presents an industry-leading digital pulse width modulation (PWM) controller that can easily and efficiently drive low-cost, 10W power bipolar junction transistor (BJT) switches to reduce the BOM cost in 5V/2A smartphone adapters and chargers. The new iW1679 allows designers to replace field effect transistors (FETs) with lower-cost BJTs and address the market trends for lower standby power and higher light-load and active average efficiency in smartphones, media tablets and consumer electronic products. Developed by Dialog's Power Conversion Business Group (formerly iWatt Inc.), the iW1679 delivers on Dialog's goal to expand its addressable market. The iW1679 reduces BOM costs while achieving high efficiency through the use of Dialog's adaptive multi-mode PWM/PFM control that dynamically changes the BJT switching frequency. This optimises the system to improve light-load efficiency, power consumption and EMI. The iW1679 provides high, 83% active average efficiency, maintains high efficiency at loads as light as 10%, and achieves <30mW no-load standby power with fast standby recovery time. This enables designers to meet or exceed emerging global energy standards, including the proposed stringent European CoC version 5(1), which is anticipated to require 76% active average efficiency and high light load efficiency down to 10% loads, as well as the proposed U.S. DoE(2) regulation, expected to require 79% active average efficiency, and the Energy Star EPS 2.0(3), which will require 73% active average efficiency. "The use of BJTs is prevalent in 5W and lower power supplies, where Dialog is a leader with a wide range of digital PWM controllers designed to drive BJTs," commented Ron Edgerton, Vice President and General Manager of Dialog's Power Conversion Business Group. "With the iW1679, we are applying this extensive knowledge to bring the same low cost, high efficiency and performance benefits to higher power applications." While BJTs reduce cost compared to FETs, BJT drive requirements are more complex. The iW1679 solves this challenge by using Dialog's patented digital control technology to actively modulate the BJT base current drive. This optimises performance and improves efficiency by keeping the BJT out of saturation. Since BJTs have softer switching compared to FETs, they generate less noise and, therefore, have inherently lower EMI. The iW1679 features Dialog's EZ-EMI®, an internal EMI technique that uses valley mode switching to further reduce EMI, simplify manufacturing and minimising the need for external EMI filtering components. It also includes a proprietary switching mode that results in no audible noise from the controller. The iW1679 lowers BOM costs up to 10%(4) compared to FET-based designs. Additional BOM cost savings come from Dialog's patented PrimAccurate™ primary-side control technology that eliminates the need for a secondary-side regulator and optical feedback isolator. The iW1679 offers a user-configurable, four-level cable drop compensation option to eliminate the ordering and inventory challenges of stocking multiple product versions for various output voltage needs. It comes in a standard, low-cost, 8-lead SOIC package and offers full protection from fault conditions, including output short-circuit, output over-voltage, output over-current, and over-temperature protection. Dialog Semiconductor