The lowest cost LED fluorescent lamp driver solution on the market

As a new type of light source, LED has attracted wide attention for its energy saving, long life and no pollution. However, from the perspective of the domestic market, it still takes a long time to replace traditional energy-saving lamps. However, in my opinion, the current LED market can only open up the domestic LED lighting market if the quality is guaranteed and the price is reasonable.

At present, Taiwan Digital Energy Technology has developed an IC NU501 specifically for LED lighting, which realizes a low-cost constant current drive solution. The total cost of the entire constant current drive power supply is about RMB 2 yuan. The following is a specific solution description:

Nu501 is a newly designed linear LED constant current driver IC, packaged as sot 23-3, with an application voltage range of 0.4-12V and an output current of 15-60mA. Due to the high withstand voltage, in the application of multiple lamps in series, only a small number of external components are needed to realize AC input application. Compared with the traditional application circuit, it not only saves the isolation transformer, but also reduces the volume and design cost of the entire system. 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 outputs DC after passing through the rectifier bridge.

2. Selection of C1 capacitor

C1 in the circuit is an electrolytic capacitor, which mainly plays a filtering role and can improve efficiency. To ensure higher efficiency, it is best to use 10UF or more, because 220V AC is 311V DC after rectification, and the estimated voltage resistance of the capacitor should be above 300V.

3. The MOS switch tube in the circuit is mainly responsible for the voltage drop. For example, if 75 LED lamp beads are connected in series in the circuit, the voltage drop on the MOS tube is about 70V. Therefore, its heat generation will be relatively large, and a heat sink is required for heat treatment. In order to reduce the heat dissipation, a MOS switch tube with a larger current can also be used.

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

Test data:

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

The following are pictures of the actual test data

Figure: Test sample