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Primary Side Sensing Controller Benefits From Transistor Advances

Primary Side Sensing Controller Benefits From Transistor Advances

CamSemi announced recent advances in the company's bipolar transistor (BJT) drive scheme and the first of a new generation of Primary Side Sensing (PSS) controllers to exploit these developments.  The new C2172 PSS controller will enable manufacturers to develop what the company believes will be the industry's lowest cost, most energy-efficient BJT-based solutions for mobile phone chargers and other universal input applications rated to 6.5 W.  The new drive scheme will also help designers improve the ruggedness of their designs.

CamSemi's proprietary BJT drive technology uses combined base and emitter switching to boost switching performance and deliver higher operating efficiencies, more Reverse Bias Safe Operating Area (RBSOA) margin and the flexibility to accommodate a wide range of low cost BJTs.  Competitive drive schemes control just one transistor node which can impact operating efficiency, cut the RBSOA margin and reduce design robustness unless several additional components are included to counteract this.

C2172 is the first CamSemi PSS controller to combine this powerful new drive scheme with the company's industry-proven PSS technology to deliver no-load power consumptions well below 30 mW and 'best in class' load-transient response but with significantly lower system cost and component counts.  The IC power consumption and design have also been optimised to enable the benefit of fast start but without needing the additional cost and complexity of an additional active start-up switch.  CamSemi's next generation PSS controller is also fully compliant with all the newly emerging standards for 'MoU' compliant universal USB chargers.

C2172 also incorporates many of the same key design benefits as the company's existing PSS controller families including: accurate current and voltage regulation of +/- 5% without board-level trimming; quasi-resonant switching to reduce EMI and to enable compliance with efficiency standards with additional manufacturing margin; and full protection features.

The new controller is packaged in a SOT23-6 for small footprint designs, samples are available now.

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