UCC38502
FEATURES
D bines PFC and Downstream Converter
Controls
D Controls Boost Preregulator to Near-Unity
Power Factor
D Accurate Power Limiting D Improved Feedforward Line Regulation D Peak Current-Mode Control in Second Stage D Programmable Oscillator D Leading-Edge/Trailing-Edge Modulation for
Reduced Output Ripple
D Low Start-up Supply Current D Synchronized Second Stage Start-Up, with
Programmable Soft-start
D Programmable Second Stage Shutdown
DESCRIPTION
The UCC2850x family provides all of the control functions necessary for an active power-factorcorrected preregulator and a second-stage dc-to- dc converter. The controller achieves near-unity power factor by shaping the ac input line current waveform to correspond to the ac input-line voltage using average current-mode control. The dc-to-dc converter uses peak current-mode control to perform the step-down power conversion.
The PFC stage is leading-edge modulated while the second stage is trailing-edge synchronized to allow for minimum...
