Unitrode Corp. (Merrimack, NH) announced the UCC39421/2 family of multimode high-frequency PWM controllers, optimized for low-power portable applications. The ICs are considered ideal for multi-chemistry battery applications, whether using alkaline, NiMH rechargeable, or lithium-ion rechargeable cells.The UCC39421 family is claimed to offer 95 percent efficient, current-mode dc/dc conversion to boost, flyback, and SEPIC (Single Ended Primary Inductance Converter) control topologies. The devices can operate down to 1.8V input and drive either external p-channel or n-channel MOSFETs, and all converter topologies can be configured to operate at fixed frequencies as high as 2MHz. The boost topology of the UCC39421/2 is considered ideal by Unitrode for portable applications where primary power is provided from two or three primary alkaline or NiMH rechargeable batteries. A user-programmable current threshold comparator commands variable-frequency operation for optimum efficiency at low output power levels. The converter frequency can also be synchronized to an external clock. The devices also feature a programmable power-on-reset function and an uncommitted comparator for low-voltage detection, as well as pulse-by-pulse current limiting and low current shutdown(5uA). The UCC39421 is priced at $3.00 and the UCC39422 is priced at $3.35, both in 1,000-piece quantities. The UCC39421 is offered in 16-pin TSSOP (PW) or DIL (N) packages, and the UCC39422 is offered in 20-pin PW or N packages. Temperature ranges are -40 to 85 degrees C for the UCC29421/2 and 0 to 70 degrees C for the UCC39421/2.