Interleaved PWM Controllers Facilitate Brick Building

Two single-chip interleaved pulse-width-modulation (PWM) controllers from Texas Instruments simplify the design of isolated offline power supplies and dc-dc converters ("bricks") with 50 to 100 A of output. The UCC28220 and UCC28221 peak current-mode controllers integrate two PWM channels operating 180° out of phase to control one high-current output.

Whether they come in an interleaved forward or interleaved flyback isolated topology, the controllers offer a host of features. Programmable internal slope compensation with an internal circuit precisely matches currents between the two channels. A maximum duty cycle clamp can be programmed from 60% to 90% duty cycles per channel. A 2-MHz programmable oscillator enables up to 1-MHz operation per channel. And, the UCC28221's 110-V startup device eliminates the need for an external trickle-charge boot-strap resistor.

Available now in 16- and 20-pin SOPs and TSSOPs, the chips cost $1.49 ('28220) and $1.57 ('28221) each in lots of 1000. Texas Instruments also offers half-brick evaluation modules that include a 200-W, 48- to 12-V converter.