Each quarter, Fairchild Semiconductor introduces new products, tips and tools for power and analog applications in the quarterly Benchmarks magazine. The following Benchmarks Volume 1, 2010 “Engineering Connections” article discusses flyback topology as an efficient solution for meeting today’s global demand for lowering power consumption in power supplies.

External power adapters are instrumental for the operation of virtually all small electronic devices. As many as 3.2 billion adapters are currently in use globally, according to industry estimates.

With this worldwide focus on energy savings, regulatory bodies are examining all ways to “go green,” and standards have been developed, specifying higher levels of efficiency for products such as notebook PC power supplies. Flyback topology has proven to be an effective solution, both in terms of cost and technology, for pulse-width modulated (PWM) power conversion in these products. Fairchild has a wide portfolio of PWM controllers  that enhance the performance of flyback converters.

As part of its global focus on energy savings, Fairchild has developed a portfolio of pulse-width modulated (PWM) controllers, which enable notebook power-supply designers to meet the stringent international energy-saving regulations. These include the ENERGY STAR External Power Supply (EPS) version 2.0 requirement that mandates 87 percent average active-mode efficiency to obtain compliance.

Integrated PWM controllers, like the FAN6754, offer designers high-voltage startup to improve energy savings at light load by 25 percent when compared to alternate solutions. It also eliminates external protection circuits by incorporating over-voltage, over-current and over-temperature protection plus brownout and line-compensation functions. Other advantages of Fairchild’s PWM controllers include frequency hopping, which reduces EMI emissions by as much as 5-10 dB, and internal soft start (8ms) to reduce voltage stress on the MOSFET at startup.

Additionally, Fairchild’s PWM controllers incorporate several design features that lower the overall power consumption of notebook adapters, such as a proprietary green-mode function that provides off-time modulation to continuously decrease the switching frequency under light-load conditions. Fairchild’s PWM devices offer a host of robust, accurate protection features built-in to protect the power supply and the load from failure, all without adding external components or circuitry.

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