DESCRIPTION

· The UCC2850x family integrates control functions for active power-factor-corrected preregulators and second-stage DC-to-DC converters.
· Achieves near-unity power factor by shaping AC input current to match AC input voltage using average current-mode control.
· Features peak current-mode control in the DC-to-DC converter for step-down power conversion.
· Includes leading-edge modulation for PFC stage and trailing-edge synchronization for the second stage to minimize ripple current.
· Utilizes line feedforward (V FF) to maintain constant input power across varying input voltages, reducing external parts and avoiding high-voltage components.
· Offers over-voltage protection, zero-power detection, and peak current and power limiting in the PFC section.
· DC-to-DC section features current limiting, controlled soft-start, and a 50% maximum duty cycle.
· Available in 20-pin N and DW packages with varying UVLO thresholds for different operational needs.

FEATURES

· Combines PFC and downstream converter controls.
· Controls boost preregulator to achieve near-unity power factor.
· Provides accurate power limiting and improved feedforward line regulation.
· Implements peak current-mode control in the second stage.
· Features a programmable oscillator and leading-edge/trailing-edge modulation to reduce output ripple.
· Low start-up supply current and synchronized second stage start-up with programmable soft-start.
· Programmable second stage shutdown.

APPLICATIONS

· Suitable for active power-factor correction in power supplies.
· Ideal for applications requiring near-unity power factor and efficient DC-to-DC conversion.
· Used in systems with wide input voltage ranges and need for reduced output ripple.
· Applicable in designs requiring low start-up current and controlled soft-start mechanisms.