原标题：基于ST L4984的600W PFC电源方案

　　L4984D是一款电流模式PFC控制器，采用线路调制固定关断时间(LM-FOT)控制。专有的LM-FOT调制器允许升压PFC转换器的固定频率操作，只要它们在CCM(连续导通模式)下工作即可。L4984采用10引脚SO封装，为EN61000-3-2和JEIDA-MITI兼容应用中的CCM操作升压PFC预调节器提供低成本解决方案，功率范围从几百W到1千瓦及以上。

　　高线性乘法器包括一个特殊电路，能够降低交流输入电流的交越失真，即使在较大的负载范围内，也可以在相当低的THD下进行宽范围电源操作。输出电压通过电压模式误差放大器和精确的(Tj = 25°C时为1%)内部参考电压进行控制。通过电压前馈功能优化环路稳定性，L4984采用专利技术，在电源下降和浪涌(“双向”)的情况下也显著改善线路瞬态响应。

　　L4984功耗低，并具有适用于IC远程开/关的Latch功能。这些功能允许在符合最新节能要求的应用中使用。除了能够在瞬态条件下控制输出电压的过压保护外，IC还具有防止反馈环路故障或错误设置的保护。其他板载保护功能可以安全地处理掉电条件和升压电感饱和。软启动限制峰值电流并延长关断时间以防止初始循环中的磁通失控。图腾柱输出，驱动具有600 mA和800 mA能力，适用于大型MOSFET或IGBT驱动。

　　场景应用图

　　展示板照片

　　方案方块图

　　核心技术优势

　　1.软启动

　　2.输入Feed Forward功能

　　3.市电欠压侦测，输出过压保护

　　4.电感饱和侦测

　　5.保护具有Auto recovery与Latched 的设定

　　方案规格

　　1.90~264VAC输入

　　2.400V/600W输出

　　3.EFF达97%以上

　　4.THD 20%以下

　　技术文档

　　【L4984D】

　　CCM PFC CONTROLLER

　　The L4984D is a current-mode PFC controller operating with line-modulated fixed-off-time (LM-FOT) control. A proprietary LM-FOT modulator allows fixed-frequency operation for boost PFC converters as long as they are operated in CCM (continuous conduction mode).

　　The chip comes in a 10-pin SO package and offers a low-cost solution for CCM-operated boost PFC pre-regulators in EN61000-3-2 and JEIDA-MITI compliant applications, in a power range that spans from few hundred W to 1 KW and above.

　　The highly linear multiplier includes a special circuit, able to reduce the crossover distortion of the AC input current, that allows wide-range-mains operation with a reasonably low THD, even over a large load range.

　　The output voltage is controlled by means of a voltage-mode error amplifier and an accurate (1% at Tj = 25 °C) internal voltage reference. Loop stability is optimized by the voltage feedforward function (1/V2correction), which in this IC uses a proprietary technique that also significantly improves line transient response in the case of mains drops and surges (“bi-directional”).

　　The device features low consumption and includes a disable function suitable for IC remote on/off. These features allow use in applications which also comply with the latest energy saving requirements (Blue Angel, ENERGY STAR, Energy 2000, etc.).

　　In addition to overvoltage protection able to keep the output voltage under control during transient conditions, the IC is also provided with protection against feedback loop failures or erroneous settings. Other onboard protection functions allow that brownout conditions and boost inductor saturation can be safely handled. Soft-start limits peak current and extends off-time to prevent flux runaway in the initial cycles.

　　The totem pole output stage, capable of 600 mA source and 800 mA sink current, is suitable for big MOSFETs or IGBT drive.

　　Key Features

　　Line-modulated fixed-off-time (LM-FOT) control of CCM-operated PFC pre-regulators

　　Proprietary LM-FOT modulator for nearly fixed-frequency operation

　　Proprietary multiplier design for minimum THD of AC input current

　　Fast “bi-directional” input voltage feedforward (1/V2correction)

　　Accurate adjustable output overvoltage protection

　　Protection against feedback loop failure (latched shutdown)

　　Inductor saturation protection

　　AC brownout detection

　　Digital leading-edge blanking on current sense

　　Soft-start

　　1% (at Tj = 25 °C) internal reference voltage

　　- 600 / + 800 mA totem pole gate driver with active pull-down during UVLO and voltage clamp

　　SSOP10 package