UC3854 - Unisonic Technologies

UC3854 ENHANCED HIGH POWER FACTOR PREREGULATOR

The UTC UC3854 provide all the functions necessary for active power factor corrected preregulators. The controller achieves near unity power factor by shaping the AC input line current waveform to correspond to that of AC input line voltage. Average current mode control maintains stable, low distortion sinusoidal line current without the need for slope compe.

Features

such as wide bandwidth, low offset Current Amplifier, a faster responding and improved accuracy enable comparator, a VREF "good" comparator, UVLO threshold options (16/10V for offline, 10.5/10V for startup from an auxiliary 12V regulator), lower startup supply current, and an enhanced multiply/divide circuit. New features like the improved amplifier current sinking capability, amplifier output clamps, and low offset VAC pin reduce the external component count while improving performance. Improved common mode input range of the Multiplier output/Current Amp input allow the designer greater flex.