Single-Chip Power Factor Control for 75- to 800W Consumer Applications

TI's UCC28060 two-phase high-performance controller for 75- to 800-W applications simplifies power system design, minimizes switching losses, and saves system cost and valuable board space when compared to traditional single-phase, transition-mode topologies or continuous-conduction mode (CCM) topologies. In certain customer applications, designers have been able to reduce their overall bill of

materials cost by as much as 20 percent, while achieving higher levels of performance in a smaller, thinner and lighter power supply design.



The UCC28060 efficiently meets the world's most stringent power factor requirements for consumer electronic systems. The device features Natural InterleavingT technology, which reduces the amount of input and output current ripple, distributes magnetics to improve thermal management, and provides light-load phase management. The UCC28060's ripple cancellation feature significantly reduces ripple current compared to single-phase or alternative master-slave interleaved solutions. In addition, the feature allows a designer to reduce capacitor size by 27 percent, and it gives designers the ability to use

a smaller, less expensive electromagnetic interference (EMI) filter.



The PFC controller's light-load phase management enables a power supply to operate at high efficiency over the range of the load, enhancing system performance and aiding OEMs' efforts to achieve 80 Plus and Energy Star compliance. Phase management allows the user to turn on or

off phases of the power supply so that only the phases required to power the load are enabled. The UCC28060 can increase efficiency by up to five percent at light load conditions.



Safety is a critical concern of all power system designers, and the UCC28060 offers several unique system control and protection features to improve power system reliability. The UCC28060 incorporates the industry's first failsafe over-voltage protection circuit, which provides dual paths of voltage sensing to protect against shorts to an intermediate voltage. If undetected, such shorts could lead to a

catastrophic failure on the board. Second, the PFC device provides in-rush current management to prevent MOSFET conduction during in-rush events, while eliminating reverse recovery events in the system output rectifiers. Finally, the UCC28060 employs sensorless current shaping to

protect the system from potential damage that may otherwise occur during brown-out conditions and recovery.



Samples of the UCC28060 are available in a 16-pin SOIC package. It is currently sampling today, with volume production scheduled for June. Suggested resale pricing in quantities of 1,000 units is $1.30.



TI also will demonstrate at the PCIM Europe conference its Digital PFC Adapter Board, based on the TMS320F280x digital signal controller. This board helps analog and digital power supply designers evaluate and detect power factor correction in power systems that support consumer

and industrial applications. The PSFB2808 board is used with TI's F2808 eZdsp Starter Kit and free downloadable C2000 Power Factor Correction Software, and is available through Tier Electronics

(www.tierelectronics.com).