LED drive technology

Introduction: the resistance current limiting is one of the LED driving method, its advantage is the cost is low, the design is simple; the disadvantage is that the current will vary with the forward voltage and the driving voltage, so the brightness of the LED will change. When the battery voltage is high, the efficiency of the drive is poor, because most of the power will be consumed on the resistance. In addition, the current limiting resistor will produce a lot of heat, leading to the problem of heat dissipation. So this is a simple, but not the most efficient way.

The second method is a linear current regulator, also called a constant current source. It has the advantages of simple design and constant current. The disadvantage is that the efficiency is very low, and with the increase of the input voltage, the voltage drop of the linear chip will be larger, so the linear chip will also produce a lot of heat. However, it improves the current fluctuation in the current limiting method.

In addition to the above two methods, there is also a switching power supply drive method. Table 1 is a comparison of the three different methods, the use of switching power supply as a LED driven method has a high efficiency, and current constant. Due to high efficiency switching power converter, so it is more and more car manufacturers use. The biggest drawback is that the design of the line to be more complex, and the cost is relatively high.

Why do you need a boost / buck LED driver in automotive lighting? This is because the battery voltage fluctuation, voltage fluctuations, we need to maintain the constant current flowing through the LED, step-up / step-down LED drive can ensure that the input voltage is above or below the output voltage and current can be kept constant. This ensures that the safety related lighting can be kept constant when the load is off and cold start. In addition, diverse LED automotive lighting applications also require different LED driver topology. Part of the car light manufacturers want to have a LED drive platform can be applied to different lighting systems with different LED configurations. Boost / buck LED driver is an ideal driver solution for most high brightness automotive lighting systems.