The lowest cost LED fluorescent lamp drive solution uses NU501

At present, Taiwan Digital Energy Technology has developed an IC NU501 specifically for LED lighting , which realizes a low-cost constant current driving scheme. The total cost of the entire constant current driving power supply is about RMB2. The following is a specific program description:

The Nu501 is a newly designed linear LED constant current driver IC packaged in sot 23-3 with an application voltage range of 0.4-12V and an output current of 15-60mA. Due to the higher pressure, in a multi-series with the lamp, only few external components, AC input application can be achieved, compared to traditional application circuit, not only save the isolation transformer, but also reduces the overall system Volume and design cost. This product is mainly used in home lighting and landscape lighting.

Typical application circuit:

parameter settings:

1. D1~D4 form a rectifier bridge through 4 diodes , and AC220V AC passes through the rectifier bridge to output DC DC.

2, C1 capacitor selection

In the circuit, C1 is an electrolytic capacitor, which mainly plays a filtering role and can improve the efficiency. In order to ensure higher efficiency, it is better to use 10UF or more. Since 220V AC rectification is 311V DC, estimate the withstand voltage value of the capacitor. More than 300V.

3, the MOS switch tube in the circuit is mainly responsible for the voltage drop, such as the string of 75 LED lamp beads in the circuit, in this case, the voltage drop to be borne on the MOS tube is about 70V, so its heat will be compared Large, heat sinks need to be added for heat treatment. In order to reduce the heat dissipation, it is also possible to use a MOS switch tube with a larger current.

4, NU501 is a constant current design of 15ma to 60ma, so when selecting the output current, you can choose according to the current you need to achieve the constant current source you want.

Test Data:

The following table shows the test data of 150 (75 series, 2 and) 0.07W white LED lamp beads:

The following is a test real shot data picture

Figure 1: Test template

Figure 2: Test sample lighting effect

Figure 3: Current after constant current after 182V AC input is 0.034A

Figure 4: Current after constant current after 200V AC input is 0.034A

Figure 5: Current after constant current after 220V AC input is 0.034A

Figure 6: Current after constant current after 240V AC input is 0.035A

Figure 7: Finished production of LED fluorescent lamps by customers using this solution