Unitrode Corp. (Merrimack, NH) recently announced the UCC3817/8 family of new-generation power factor preregulators. Unitrode claims that these controllers will provide easy and cost-effective compliance to IEC 1000-3-2 harmonic reduction requirements for any off-line power supply (from 75W to a few kW) applications that operate over a wide or universal input voltage range (85-270Vac).These controllers operate with the average current mode controlled boost power architecture pioneered by Unitrode. Features such as leading-edge modulation, simplified input voltage feed-forward, overvoltage protection, accurate power limiting, and improved noise immunity offer added flexibility and benefits to the user.Unitrode claims that any line-connected power converter requiring PFC can benefit from the feature enhancements and improved implementation cost offered by the UCC3817. The UCC3817 has a wide UVLO range (16.5V/10V) with an on-chip shunt regulator for bootstrap bias supply operation, while the UCC3818 is designed with a narrow UVLO range (10.5V/10V) more suitable for fixed bias operation."With the UCC3817/8 we are offering our customers significant improvements in system cost and performance while allowing them to leverage their familiarity with an industry-standard PFC architecture," states Rich Valley, Business Line Director of Unitrode Power Supply Control Products. "A broad range of power factor corrected supplies will benefit from features such as reduced bulk capacitor ripple current, improved multiplier linearity, easy synchronization, and low start-up and operating currents."The UCC3817 and the UCC3818 are priced from $1.99 to $2.19 each, for quantities of 1000 or more. Standard packaging options are DIL-16 (N or J), SOICW-16 (DW), PLCC-20 (Q), and LCC-20 (L).