Date: 19/08/2011

PWM controllers supports half-bridge, full-bridge, interleaved forward and push-pull topologies

Texas Instruments Incorporated (TI) has introduced two new green PWM power supply controllers, UCC28250 and UCC28950 with integrated, programmable-delay synchronous rectifier control outputs and pre-bias start-up circuitry, which 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, which may have stringent pre-bias start-up requirements and support multiple high-efficiency topologies.

As per TI, 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, 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 UCC2825 include:
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.
Phase-shifted full-bridge control with synchronous rectification

TI also explains the UCC28950, which provides two additional PWM outputs for phase-shifted full bridge control up to 600 watts and achieves greater than 90-percent efficiency and 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, which increases efficiency by 20 percent compared to competitive devices. The UCC28950 is said to improve power supply performance in high-density power architectures for industrial, telecom and DC motor drives.

Other key features and benefits of UCC28950 include:
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.

Availability and pricing: 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.









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