Directly use 220V mains power LED lighting

With the development of science and technology, various energy-saving lamps emerge in an endless stream, especially LED lighting lamps develop rapidly, but the quality varies. Especially in the driving part of the circuit, most of the 220V LED lighting lamps on the market use simple resistors and capacitors to reduce the voltage, which does not bring out the true energy of the LED light-emitting diodes and shortens the life of the LED. Here we introduce two 220V LED lighting lamps made with the integrated circuit LNK304PN, which are not only highly efficient but also greatly extend the life of the LED light-emitting diodes and improve the utilization rate of the power supply.

The non-isolated power supply composed of LNK304PN has two basic structures, namely BUCK step-down converter and BUCK-BOOST converter, as shown in Figure 1 and Figure 2 respectively.

There are two circuits, one with positive output and the other with negative output.

The main difference between them is the wiring position of VD4 and L2. The BUCK converter connects VD4 in parallel between the source and the negative end of the input voltage, and L2 in series between the source and the positive end of the output voltage. The BUCK-BOOST converter is the opposite, which can meet the needs of various loads. LCK304PN is specially used to replace all linear and capacitor-step-down non-isolated power supplies with an output current less than 360mA. LCK304PN integrates a 700V power MOSFET and oscillator on an IC. Simple switch control circuit, high-voltage switch current source, frequency modulation, cycle-by-cycle current limit, and over-temperature protection circuit. RF in the circuit is a fusible resistor, which plays a current limiting protection role for VD1 and VD2. VD4 is an ultra-fast recovery diode. VD1, VD2 and L1, C1, C2 form a rectifier filter circuit, L2 is an energy storage inductor, and C5 is a voltage stabilizing capacitor.

The light-emitting diodes in the lamp are four in series and five in parallel. The specific circuit is shown in Figure 3. The circuit of the LCK304PN group can easily replace the power supply of those cheap RC step-down LED lighting lamps. It is safe, reliable and has a long service life. Pay attention to safety during the production process because it is a non-isolated power supply. Avoid human contact with electrical parts.