UC3854B - 增强型高功率因子前置稳压器

UC3854B是TI德州仪器公司的一款功率因数校正产品，UC3854B是增强型高功率因子前置稳压器，本站介绍了UC3854B的封装应用图解、特点和优点、功能等，并给出了与UC3854B相关的TI元器件型号供参考。

UC3854B - 增强型高功率因子前置稳压器 - 功率因数校正 - 离线隔离型DC/DC控制器和转换器 - 德州仪器

产品描述

The UC3854A/B products are pin compatibleenhanced versions of the UC3854. Like the UC3854, these products provide 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/B 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.

A 1%, 7.5-V reference, fixed frequency oscillator, PWM, voltage amplifierwith soft-start, line voltage feedforward (VRMS squarer), input supply voltage clamp, and over current comparator round out the lilst of feataures.

Available in the 16-pin N (PDIP), DW (SOIC Wide), and J (CDIP) and 20-pin Q (PLCC) package. See Ordering Information table for availability by temperature range.

The UC3854A/B products improve 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 V/10 V for offline, 10.5 V/10 V for startup from an auxiliary 12-V regulator), lower startup supply current, and an enhanced multiply/divide circuit. New features like the amplifier output clamps, improved amplifier current sinking capability, and low offset VAC pin reduce the external component count while improving performance. Improved common mode input range of the multiplier output/current amplifier input allow the designer greater flexibility in choosing amethod for current sensing. Unlike its predecessor, RSET controls only oscillator charging current and has no effect on clamping the maximum multiplier output current. This current is now clamped to a maximum of 2 × IAC at all times which simplifies the design process and provides foldback power limiting during brownout and extreme low line conditions.

产品特性

Controls Boost PWM to Near-Unity Power Factor
Limits Line Current Distortion To <3%
World-Wide Operation Without Switches
Accurate Power Limiting
Fixed-Frequency Average Current-Mode Control
High Bandwidth (5 MHz), Low-Offset Current Amplifier
Integrated Current- and Voltage-Amplifier Output Clamps
Multiplier Improvements: Linearity, 500 mV VAC Offset (Eliminates External Resistor), 0 V to 5 V Multout Common-Mode Range
VREF GOOD Comparator
Faster and Improved Accuracy ENABLE Comparator
UVLO Options (16 V/10 V or 10.5 V/10 V)
300-µA Start-Up Supply Current

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