1. Keep the main current loop PCB as short as possible. Laying PCBs is based on experience and layout; there's not much to it, but a quick way is to study the work of major manufacturers.
2. Optimize transformer parameter design to reduce eddy current losses caused by ringing. This is more difficult. First, you need to master electromagnetic fundamentals and design a reasonable transformer. The most important thing is patience; even if you think of improving efficiency by 0.5%, you should try.
3. Select appropriate switching devices. This is a balance between cost and performance. Use devices according to customer requirements, but it must be reasonable. If efficiency is paramount, then COOL MOS and low-VF output diodes are undoubtedly the best choices.
4. Optimize the input EMI section design. To pass safety regulations, this part requires more consideration and mainly relies on experience.
5. Choose a high-efficiency topology. This is the starting point for solution selection. For example, PWM and QR PFM. When the customer specifies efficiency requirements, you need to evaluate which topology to choose.
6. Choose good electrolytic capacitors. Many people overlook this. Electrolytic capacitors have significant losses. Professor Chen Yongzhen has explained this in detail in an article.
7. While ensuring efficient power consumption during startup, it's crucial to consider that many chips have high-voltage (HV) startup pins, and startup current is increasingly lower. This requires a thorough understanding of newer devices. Of course, there are also lossless startup methods using external circuits, which are not suitable for LED drivers.
8. Regarding chip auxiliary power supply optimization, ST's L6562D application documentation indicates that 15V is optimal. However, LEDs generally have a wide voltage output range. Therefore, my choice is to add a linear regulator stage to keep the chip operating at 15V to reduce losses.
