Linear公司的LT3798是绝缘无光耦带PFC的反激控制器,功率因素大于0.97,不需要光耦合器,谐波低,恒流和恒压调整,精度在±5%,无负载的功耗小于0.5W,和能源之星标准兼容,主要用在离线5W-100W电源,高DC VIN绝缘应用和离线总线转换器(12V,24V或48V输出).本文介绍了LT3798主要特性,框图以及通用输入24W和48W PFC电源电路图.

Isolated No Opto-Coupler Flyback Controller with Active PFC

The LT®3798 is a constant voltage/constant current isolated flyback controller that combines active power factor correction (PFC) with no opto-coupler required for output voltage feedback into a single-stage converter. A LT3798 based design can achieve a power factor of greater than 0.97 by activELy modulating the input current, allowing compliance with most Harmonic Current Emission requirements.

The LT3798 is well suited for a wide variety of off-line applications. The input range can be scaLED up or down, depending mainly on the choice of external components.

Efficiencies higher than 86% can be achieved with output power levels up to 100 watts. In addition, the LT3798 can easily be designed into high DC input applications.

LT3798主要特性:

Isolated PFC Flyback with Minimum Number of External Components

VIN and VOUT Limited Only by External Components

Active Power Factor Correction

Low Harmonic Distortion

No Opto-Coupler Required

Constant-Current and Constant-Voltage Regulation

Accurate Regulated Voltage and Current (±5% Typical)

Energy Star Compliant (<0.5W No Load Operation)

Thermally Enhanced 16-lead MSOP Package

LT3798应用:

Offline 5W to 100W+ Applications

High DC VIN Isolated Applications

Offline Bus Converter (12V, 24V or 48V Outputs)

图1. LT3798方框图

图2. LT3798通用输入24W PFC总线电源电路图

图3. LT3798通用输入48W PFC电源电路图