UC3854AN

The UC3854AN is an enhanced high Power Factor Preregulator provides all of 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 the ac input line voltage. To do this the UC3854A uses average current-mode control. Average current-mode control maintains stable, low distortion sinusoidal line current without the need for slope compensation, unlike peak current-mode control. It is improved upon the UC3854 by offering a 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.

• Controls boost PWM to near-unity power factor
• Limits line current distortion to <lt/>3%
• World-wide operation without switches
• Accurate power limiting
• Fixed-frequency average current-mode control
• Low-offset current amplifier
• Integrated current- and voltage-amplifier output clamps
• Faster and improved accuracy ENABLE comparator
• Green product and no Sb/Br