Adding to its pulse-width modulator (PWM) power management controllers, Texas Instruments has introduced a controller for unregulated output voltages that it claimed will achieve up to 97 per cent system efficiency in an intermediate bus architecture. 

The UCC28230 PWM controller supports both the half-bridge and full-bridge topologies. It has a start-up frequency control feature that limits output inductor ripple current.

The controller implements load-dependent dead-time control to improve efficiency over the entire output load range. It also has 1-D output that shorts the primary-side winding, which keeps the self-driven synchronous rectifiers under control during start-up and shut-down and through transient conditions.

The UCC28230 includes a precision 5V reference voltage output for general-purpose voltage biasing. There is also a precision 3.3V reference voltage output for the same purpose.

See http://www.ti.com