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Power adapter solution delivers 88% efficiency

Posted: 27 Jun 2006 ?? ?Print Version ?Bookmark and Share

Keywords:ON Semiconductor? GreenPoint reference design? power adapter?

ON Semiconductor unveiled it's fifth GreenPoint reference design!this one for 60W power adapters used to power LCD TVs and monitors, notebooks and other consumer products. According to the company, this new reference design addresses the sometimes tedious design challenges inherent in meeting both standby and active mode energy efficiency regulations and promises to offer a cost effective solution.

According to ON Semi, its latest design blueprint addresses all functional blocks of the power adapter and achieves low standby power and compliance with CEC, Energy Star and European Code of Conduct (COC) requirements. It promises 88 percent energy efficiency and further conserves energy in standby mode!the mode in which power adapters typically spend the most time!by consuming less than 250mW of power. Today, most 60W adapters in use are consuming 750mW in standby mode, the company said.

"The new 60W power adapter reference design joins our previously announced 90W GreenPoint notebook adapter design," said Andy Williams, senior VP of ON Semiconductor's Automotive and Power Supply Group. "This particular design addresses applications where high efficiency and adapter size are crucial at an optimal cost. By the end of the year, ON Semiconductor plans to introduce additional GreenPoint reference designs to cover a wide variety of power applications."

The enabling device for the reference design is the newly introduced NCP1337, an enhanced pulse width modulation (PWM) current-mode controller. It combines a true current-mode modulator and a demagnetization detector!that ensures full borderline/critical conduction mode in any load/line. The device eliminates the need for an external signal, by providing internal transformer core reset detection. Frequency is internally limited to 130kHz to facilitate the compliance with EMI conducted emission standards, the lowest limit being 150kHz.

By monitoring the feedback pin activity, the NCP1337 enters ripple mode as soon as the power demand falls below a pre-determined level. Because restart is softened by an internal soft-start and the frequency cannot fall below 25kHz, no audible noise is emitted. The controller features an efficient protective circuitry that, in the presence of an overcurrent condition, disables the output pulses and enters a safe burst mode when trying to restart. Once the default has gone, the device auto-recovers and the power supply resume operation.

Additional features include a bulk voltage monitoring function known as brown-out protection, an adjustable overpower compensation that tackles the effect of the input voltage variation on the maximum power a quasi-resonance PSU can deliver, and an Over Voltage Protection on the VCC. An internal 4ms soft-start eliminates the traditional startup stress.

The NCP1337 is suitable for use in power adapters, offline battery chargers, CRT-TV power supplies, other consumer electronics such as DVD players and STBs!primarily any power supply where efficiency and low EMI signature are needed.

The device is offered in both an SOIC-7 and a PDIP-7 package and priced at $1.04 per unit in 2,500-unit quantities.

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