LED lighting drive solution selection

In the design of LED lighting, there are two kinds of driving schemes: linear drive and switch type drive.

线性驱动应用是一种最为简单和最为直接的驱动应用方式。在照明级白光LED应用中，虽然存在着效率低、调节性差等问题，但是由于其电路简单、体积小巧，能满足一些特定的场合应用较多。

Linear drive application is one of the most simple and the most direct drive applications. In the application of white LED lighting level, although there are many problems, such as low efficiency, poor adjustment and so on, but because of its simple circuit, small size, can meet some specific occasions more applications.

而开关型驱动可以获得良好的电流控制精度和较高的总体效率，应用方式主要分为降压式和升压式两大类。降压式开关驱动是针对电源电压高于LED的端电压或者是多个LED采用并联驱动情况下的应用。升压式开关驱动是针对电源电压低于LED的端电压或者是多个LED采用串联驱动情况下的应用。

And switch mode driver can obtain good current control accuracy and higher overall efficiency, the main application is divided into two categories of the buck and boost. Buck switch driver is for the power supply voltage is higher than the LED of the terminal voltage or the use of multiple LED parallel driver. Boost switch driver is for the power supply voltage is lower than the LED of the terminal voltage or the use of multiple LED series driver.

一般认为，隔离型驱动安全但效率较低，非隔离型驱动效率较高，应按实际使用的要求来选。

It is generally believed that the isolation type drive safety, but the efficiency is low, the non isolation type drive efficiency is higher, should be based on the actual use of the requirements to choose.

目前设计一般的基本LED驱动器照明应用相对较简单，但是如果还需要其它功能如相位控制调光和功率因子校正(PFC)，设计就变得复杂。无功率因子校正功能的非调光LED驱动器通常包含一个离线式开关电源，用于恒定电流下调节输出。

At present, the design of the basic LED driver lighting applications is relatively simple, but if you still need other features such as phase control dimming and power factor correction (PFC), the design becomes complex. The non dimming LED driver without power factor correction function usually contains an off-line switching power supply, which is used to adjust the output under constant current.

LED驱动器的后端架构包含一个具有短路保护功能的电流调节电路。可以利用线性调节电路达到这一目的，然而这种方法本身效率低下，因此适用低输出电流，通常不会应用到多级架构中去。替代方法是使用简单的、具有电流回馈功能的降压稳压器电路，以便限制了输出电流超过期望的LED驱动电流。其抵消了总LED正向电压随温度和器件容差的变化，还限制了出现短路或其它故障条件时的电流，从而能够保护驱动器免遭损坏。

The back end of the LED driver contains a current regulation circuit with a short circuit protection function. The linear regulator circuit can be used to achieve this goal, however, this method is inefficient, so it is suitable for low output current, which is usually not applied to multi level architecture. Alternative is to use a simple, with a current feedback voltage regulator circuit, in order to limit the output current exceeds the desired LED drive current. The variation of the total LED forward voltage with the temperature and the tolerance of the device is offset, and the current is limited by the occurrence of short circuit or other fault conditions, thereby protecting the driver from damage.