illustrate

The UCC2850x family provides all the control functions needed for power factor correction preregulators and an active second-stage DC-DC converter. The controller implements a power factor close to 1 by shaping the AC input current waveform corresponding to the AC input line voltage using average current mode. The DC-to-DC converter uses peak current control mode to perform step-down power conversion.

The PFC stage is the advanced modulation, while the second stage is the minimum allowable synchronous increase of the trailing edge between the overlap and the PWM switch. This reduces capacitor. In order ripple current bulk output operation more than three to one input line voltage in the range of three to one, line feed-forward (five_FFIt is an input used to maintain a constant input supply voltage.

characteristic

• Combines PFC and downstream converter control
• Controls the boost preregulator to near power factor
• Precise power limiting
• Improved feed-forward line adjustment
• The peak current mode is controlled in the second stage
• Programmable oscillator
• Leading-Edge/Trailing-Edge modulation reduces output ripple
• Low start-up current
• The second stage starts synchronous action with programmable soft-start
• The second stage is programmable shutdown