Three common LED street light power supply design solutions

The first thing to share for everyone is the LED street light power solution, which is an indirect AC output, which is designed for constant current monitoring of 6 strings of LEDs. This design idea is currently the most expensive design on the market and the lowest channel profit. The circuit design is shown in Figure 1. As can be seen from Fig. 1, in this LED power supply scheme, the indirect optical contactor is used to stop the backtracking of the advanced side path and to regulate the input voltage. Compared with some lighting solutions used in domestic applications, the program has less power consumption. The voltage of CS is flowing at 0.25V, and constant current is mastered for 6-string LED discrimination. The IC will detect the status of the FB, and the lowest voltage of the LED will be flowing at 0.5V. This is because the total number of Vf values ​​of the strings of LEDs is inconsistent, and the voltage drop that occurs will fall on the MOS tube and cause some consumption. If it is normal for the Vf sub-BIN to select the current LED, the consumption should be able to grasp within 2%, less than the normal gate consumption.

LED street light power circuit design

Compared with the traditional street lighting design, this new solution has the advantages of high frequency and low profit, and is suitable for street lamps that can be indirectly output by AC. Correspondingly, the biggest problem with this solution lies in the development profit of AC output demand.

The second LED power solution to be shared for you is a DC or battery pack output. For 6-string LEDs, the street lighting design with constant current control is designed. The scheme mainly adopts a multi-string heating structure assumption, and its own LED driving form is similar to the first one, and the main difference between the two is that the AC output is changed to DC or is output by the battery pack. The circuit design drawing of the scheme is shown in Figure 2 below.

From the design drawing of Figure 2, we can see that in this power system, if the high-voltage side sensing needs to meet the lighting requirements, the appropriate MOS tube should be selected, and the LEDs can be equal in series under the premise of selecting the FET. More lighting. Absolutely for the AC output plan, this design is relatively easy, but because there is one more temperature-increasing gate in this power system design, the frequency is absolutely lower. Compared with the first scheme, the advantage of this design scheme is that the concept is easy and the profit of the channel is low, and the disadvantage is that the frequency is low. In practical applications, the solution is more suitable for moonlight battery packs for night illumination or street lamps with adapted re-output.

LED street light power circuit design

The LED street light power supply with single-string buck structure is the third most common design we have to share for you. The circuit system drawing of this design scheme is shown in Figure 3 below. As a solution that can realize modular design, the modification of the scheme is relatively simple. However, the drawback is that each string needs an independent power module. Compared with the first two schemes, the production profit is higher, but lower. The pressure configuration will limit the number of LEDs to the IC's withstand voltage. As can be seen from Figure 3, there are at most 14 LEDs in this power system. If you want to envision a 20W light bar, you need to use a 700mA LED. In order for the frequency to reach the highest, the output voltage must be tuned to the number of LEDs, that is, to the heavy input voltage. Taking 10 LEDs as an example, if you want to reach the highest frequency, you must adjust the output voltage to about 42V.

LED street light power circuit diagram

Compared with the two solutions described above, the advantage of this LED power supply design is that the buck configuration frequency is high, the sensitivity of the single-string design and configuration is relatively high, and the street lamp with adaptive re-output should be adopted. The disadvantage is that the path profit is high, and the number of LED parallel connections is limited by the IC withstand voltage during the design process.

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