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ON Semi PWM controller lowers system cost

Posted: 01 Mar 2004 ?? ?Print Version ?Bookmark and Share

Keywords:on semiconductor? ncp1280? pwm controller?

ON Semiconductor has disclosed that its NCP1280 voltage mode PWM controller is the first in the industry to offer a high-voltage start-up (up to 700V) for active clamp circuits.

The NCP1280 provides a highly integrated solution for off-line power supplies requiring high efficiency and low parts count. It provides control outputs for driving a forward converter primary MOSFET and an auxiliary MOSFET for active clamp circuit. The second output with its programmable delay can also be used for driving a synchronous rectifier on the secondary or for asymmetric half bridge circuits.

Targeted for use in computing power supplies, telecom front-end power systems and high-end consumer equipment such as plasma or LCD TVs, the device features a voltage feedforward, adjustable maximum duty cycle control, adjustable oscillator frequency up to 500kHz, line under and overvoltage detectors, dual mode overcurrent protection, and soft start.

Compared to traditional forward converter topologies, an active clamp solution implemented with the NCP1280 offers lower switching and conduction losses, requires a smaller output inductor and lowers the voltage across primary switches and secondary rectifiers.

Offered in a SOIC-16 package, the IC is priced at $1.90 in 10,000-unit quantities.

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