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PWM controllers boast up to 95% efficiency

Posted: 19 Aug 2011 ?? ?Print Version ?Bookmark and Share

Keywords:PWM controller? power supply? industrial system?

Texas Instruments Inc. (TI) has rolled out two high-efficiency PWM 'green' controllersUCC28250 and UCC28950that simplify design and boost efficiency in high-density isolated power supplies for telecommunications, server and industrial systems.

The UCC28250 is touted as the industry's first half bridge or full bridge PWM controller that can maintain a monotonic output voltage ramp under pre-biased load conditions, eliminating the need for external circuitry. It can support primary- or secondary-side control and delivers up to 95 percent efficiency and high power density in high-input voltage isolated DC/DC applications, such as power modules used in wireless base stations or industrial power systems.

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Both the UCC28250 and UCC28950 support multiple high-frequency topologies, such as half-bridge, full-bridge, interleaved forward and push-pull.

The UCC28250 features integrated synchronous rectifier outputs that minimize conduction loss and one percent accurate pulse-by-pulse current limit. It also has current mode and voltage mode control options that provide flexibility, TI noted.

The UCC28950, on the other hand, provides two additional PWM outputs for phase-shifted full bridge control up to 600W and achieves greater than 90 percent efficiency. The advanced controller integrates synchronous rectifier control and provides adaptive zero voltage switching over a wide input and output voltage range to reduce switching loss, increasing efficiency by 20 percent compared to competitive devices, claimed TI. The device improves power supply performance in high-density power architectures for industrial, telecom and DC motor drives.

The controller allows designers to choose half-bridge with voltage mode or full-bridge with voltage/current mode for faster response and offers light load management that improves efficiency by 70 percent. It also has 50C100 percent lower input and output ripple current that allows use of smaller input and output capacitors.

Both devices support multiple high-frequency topologies, such as half-bridge, full-bridge, interleaved forward and push-pull that may have stringent pre-bias startup requirements. They also ease various modeling and component selection tools to help speed power supply design, including PSpice transient models, PSpice average models, MathCAD design tools, applications notes, evaluation modules and power supply reference designs.

The UCC28250 and UCC28950 are available in volume from TI and its authorized distributors in a thermally enhanced 4 x 4mm, 20-pin QFN or TSSOP package. Suggested resale pricing for the UCC28250 is $1.70 in 1,000-unit quantities and $4.25 for the UCC28950.

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