UC3854N

The UC3854N is a High Power Factor Preregulator that 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 analogue multiplier/divider, a current amplifier and a fixed-frequency PWM. In addition, the UC3854 contains a power MOSFET compatible gate driver, 7.5V reference, line anticipator, load-enable comparator, low-supply detector and over-current comparator. The UC3854 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.

• Control boost PWM to 0.99 power factor
• Limit line current distortion to <lt/>5%
• World-wide operation without switches
• Feed-forward line regulation
• Average current-mode control
• Low noise sensitivity
• Low start-up supply current
• Fixed-frequency PWM drive
• Low-offset analogue multiplier/divider
• 1A Totem-pole gate driver
• Precision voltage reference
• Green product and no Sb/Br