Eight tips to improve LED driver efficiency

　　1. The main current loop PCB should be as short as possible. Experience in LAYPCB and layout, this is nothing, the quick way is to look at more works of big manufacturers.

　　2. Optimize transformer parameter design to reduce eddy current loss caused by ringing. This is more difficult. First, you need to master the basic knowledge of electromagnetics and design a reasonable transformer. The most important thing is patience. Even if you think you can improve the efficiency by 0.5%, you should try it.

　　3. Choose the switch device reasonably. This is the balance between cost and performance. What kind of device should be used according to the customer's requirements, but it must be reasonable. If you want efficiency, COOL MOS and low VF output diodes are undoubtedly the best.

　　4. If the optimized design of the input EMI part is to pass the safety regulations, this part requires more consideration and mainly depends on experience.

　　5. Choose a high-efficiency topology structure. This is the beginning of solution selection, such as PWM and QR PFM. When customers put forward efficiency requirements, it is necessary to evaluate what kind of topology to choose.

　　6. Choose a good electrolytic capacitor. Many people ignore this. The loss of electrolytic capacitors is very large. Teacher Chen Yongzhen has a detailed explanation in an article.

　　7. Under the premise of efficient power consumption design of the startup part, we need to consider that many chips currently have HV startup pins, and the startup current is getting lower and lower. This requires more knowledge about new devices. Of course, there are also lossless startup of external circuits, etc., which I think are not suitable for LED driving.

　　8. We can see that the chip auxiliary power supply optimization is pointed out in ST's L6562D application document that 15V is the best, but LEDs generally have a wide voltage output, so my choice is to add a linear voltage regulator to make the chip work at 15V to reduce losses.