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PWM controller reduces cost for smartphone power supplies

Posted: 20 Sep 2013 ?? ?Print Version ?Bookmark and Share

Keywords:smartphone? power supplies? PWM controller? bipolar junction transistor?

Dialog Semiconductor has announced what it says is the industry's first digital pulse width modulation (PWM) controller capable of driving low-cost, 10W power bipolar junction transistor (BJT) switches to reduce the BOM cost in 5V/2A smartphone adapters and chargers. According to the firm, the iW1679 lets designers 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.

The iW1679 features Dialog's adaptive multi-mode PWM/PFM control that claims to dynamically change the BJT switching frequency. This optimises the system to improve light-load efficiency, power consumption and EMI. The iW1679 provides high, 83 per cent active average efficiency, maintains high efficiency at loads as light as 10 per cent, and achieves 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 claims to lower BOM costs up to 10 per cent 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.

The iW1679 is available in production quantities and is priced at $0.29 each in 1000-piece quantities.

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