UC3854中文资料ENHANCED HIGH POWER FACTOR PREREGULATOR数据手册UTC规格书

描述 Description

The UTC UC3854 provide all the functions necessary for activepower factor corrected preregulators. The controller achieves nearunity power factor by shaping the AC input line current waveform tocorrespond to that of AC input line voltage. Average current modecontrol maintains stable, low distortion sinusoidal line currentwithout the need for slope compensation, unlike peak current modecontrol.Designed in UTC’s Bipolar process, the UTC UC3854 offersnew

特性 Features

such as wide bandwidth, low offset Current Amplifier,a faster responding and improved accuracy enable comparator, aVREF \"good\" comparator, UVLO threshold options (16/10V foroffline, 10.5/10V for startup from an auxiliary 12V regulator), lowerstartup 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 externalcomponent count while improving performance. Improved commonmode input range of the Multiplier output/Current Amp input allowthe designer greater flexibility in choosing a method for currentsensing. Unlike its predecessor, the maximum multiplier outputcurrent is now clamped to a maximum of 2IAC at all times.A 1% 7.5V reference, fixed frequency oscillator, PWM, VoltageAmplifier with softstart, line voltage feedforward (VRMS squarer),input supply voltage clamp, and over current comparator round outthe list of features. FEATURES Controls Boost Preregulator to Near Unity Power Factor Limits Line Distortion World-Wide Line Operation Accurate Power Limiting Fixed Frequency Average Current Mode Control High Bandwidth (5MHz), Low Offset Current Amplifier Integrated Current and Voltage Amp Output Clamps Multiplier Improvements: Linearity, 500mV VAC Offset (eliminates external resistor), 0-5V Multout Common Mode Range VREF \"GOOD\" Comparator Faster and Improved Accuracy ENABLE Comparator 300uA Startup Supply Current