1. Switch constant current source
A transformer is used to convert the high voltage to low voltage, and rectify and filter to output a stable low voltage direct current. The switching constant current source is divided into isolated power supply and non-isolated power supply. Isolation refers to the output high and low voltage isolation, and the safety is very high, so the insulation of the shell is not required. Non-isolated safety is slightly worse, but the cost is relatively low. Traditional energy-saving lamps use a non-isolated power supply and use an insulated plastic shell for protection. The safety of the switching power supply is relatively high (generally the output is low voltage), and the performance is stable. The disadvantage is that the circuit is complicated and the price is high. The switching power supply has mature technology and stable performance, and is currently the mainstream power supply for LED lighting.
2. Linear IC power supply
Using one IC or multiple ICs to distribute the voltage, there are few types of electronic components, the power factor and power efficiency are very high, no electrolytic capacitor is needed, and the life is long and the cost is low. The disadvantage is that the output high voltage is non-isolated, and there is stroboscopic. It requires the housing to be protected against electric shock. The market claims that there are no (de) electrolytic capacitors and ultra-long life, all use linear IC power supplies. IC drive power has high reliability, high efficiency and low cost advantages, and is an ideal LED drive power in the future.
3. RC step-down power supply
Using a capacitor to provide driving current through its charging and discharging, the circuit is simple, the cost is low, but the performance is poor, the stability is poor, the LED is easily burned out when the grid voltage fluctuates, and the output is high-voltage non-isolated, requiring an insulated protective shell. Low power factor and short life, generally only suitable for economical low-power products (within 5W). High-power products, the output current is large, the capacitor cannot provide large current, otherwise it is easy to burn out. In addition, the country has requirements for the power factor of high-power lamps, that is, the power factor above 7W requires greater than 0.7, but the resistance-capacitance step-down power supply is far Can not reach (usually between 0.2-0.3), so high-power products should not use resistance-capacitance step-down power supply. In the market, almost all low-end products with low requirements use resistance-capacitance step-down power supplies. In addition, some low-end, high-power, low-end products also use resistance-capacitance step-down power supplies.
