UC2854N (TEXAS INSTRUMENTS)

The UC2854N is a High Power Factor Preregulator provides active power factor correction for power systems that otherwise would draw non-sinusoidal current from sinusoidal power lines. This device implements all the control functions necessary to build a power supply capable of optimally using available power-line current while minimizing line-current distortion. To do this, it contains a voltage amplifier, an analog multiplier/divider, a current amplifier and a fixed-frequency PWM. In addition, it contains a power MOSFET compatible gate driver, 7.5V reference, line anticipator, load-enable comparator, low-supply detector and over-current comparator. It uses average current-mode control to accomplish fixed-frequency current control with stability and low distortion. Unlike peak current-mode, average current control accurately maintains sinusoidal line current without slope compensation and with minimal response to noise transients.