illustrate

The UC3854A/B product is a compatibleenhanced version of Pin UC3854. Like the UC3854, these products provide all the features required for active power factor correction preregulators. The controller achieves a unit power factor close to the unit power factor by shaping the AC input current waveform corresponding to the AC input line voltage. To do this, the UC3854A/B uses average current mode control. Average current-mode control remains stable, and low-distortion sinusoids do not require slope compensation currents unlike peak current-mode control.

A 1%, 7.5 V reference, fixed frequency oscillator, pulse width modulation, voltage amplifier with soft start, line voltage feed-forward_（VRMS squared), input supply voltage clamp, more than lilst feataures is currently relatively round.

characteristic

• PWM control boosts to near power factor
• Limit line current distortion
• Global action, no switches
• Precise power limiting
• Fixed frequency average current mode control
• High bandwidth (5 MHz), low bias current amplifier
• Integrated current and voltage amplifier output clips
• Multiplier improvements: linear, 500 mV_{alternating current}Offset (no external resistors required), 0 V to 5 V Multout common-mode range
• _VGood comparison of REF
• Faster, improved accuracy allows comparison
• UVLO options (V/10, 16th, V/10 V or 10.5 V).
• 300μA start-up supply current