Power Electronics

PWM Controllers Boost Efficiency In Telecom, Industrial Power Supplies

Texas Instruments Incorporated introduced two high-efficiency PWM power supply controllers with integrated, programmable-delay synchronous rectifier control outputs and pre-bias start-up circuitry. The UCC28250 and UCC28950 "green controllers" simplify design and boost efficiency in high-density isolated power supplies for telecommunications, server and industrial systems. The devices support multiple high-frequency topologies, such as half-bridge, full-bridge, interleaved forward and push-pull, that may have stringent pre-bias start-up requirements and support multiple high-efficiency topologies.

The UCC28250 is the industry's first half bridge or full bridge PWM controller with the ability to 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.

Other key features and benefits of UCC28250:

  • Integrated synchronous rectifier outputs minimize conduction loss.
  • One-percent accurate pulse-by-pulse current limit lowers system cost and simplifies design.
  • Current mode and voltage mode control options provide flexibility.

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

Other key features and benefits of UCC28950:

  • Allows designers to choose half-bridge with voltage mode or full-bridge with voltage/current mode for faster response.
  • Light load management improves efficiency by 70 percent.
  • 50- to 100-percent lower input and output ripple current allows the use of smaller input and output capacitors.

Both controllers are supported by 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 now from TI and its authorized distributors in a thermally enhanced 4-mm x 4-mm, 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.

Texas Instruments
Part Number: UCC28250

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