LED light power supply selection

As the issue of global greenhouse gas emissions is becoming more and more serious and approaching the critical point of self-regulation of the earth, countries have introduced relevant policies, and governments around the world, including China, must implement energy-saving emission reduction (CO2) without delay. LED lamps are currently the most energy-efficient. Green environmental protection electric light source has naturally become the main choice for lighting energy saving and emission reduction. With the gradual reduction of the cost and price of LED lamps, the popularity of the LED lamps is also accelerating. Before 2020, the market share of LED lamps will exceed 50%.

LED lamp Power Supply selection is mainly considered in terms of efficiency, safety, cost, reliability, volume, and heat.
First of all, from the perspective of safety, since the current LED lights are designed with built-in power, it is not necessary to isolate the power supply. 
Secondly, considering the efficiency, the efficiency of the power supply mainly depends on the structure of the circuit and the device used. In theory, the higher the output voltage, the smaller the current, the higher the efficiency, and the lower the power consumption, the higher the efficiency. Several commonly used programs are:
A. Resistor-capacitor step-down LED lamp power supply: The efficiency of the low-cost resistor-capacitor step-down mode cannot be high, and the resistor itself consumes electric energy and generates heat, and the reliability is low.
B. MOS LED lamp power supply: use MOSFET as the switching tube, the final LED fluorescent lamp power factor can be up to 0.9, because the MOSFET itself consumes at least 0.5W. Using MOSFETs is much less than switching with a triode.
C. RCC LED lamp power supply: RCC (Ringing Choke converter) is a self-oscillating pulse converter composed of intermittent oscillators. It is commonly used in low-cost low-power Led Power Supplies , and usually has a high failure rate.
D. The current-limiting LED lamp power supply (quasi-constant current LED lamp power supply) is the primary circuit in the power supply operation, setting a current threshold. When the primary MOSFET is turned on, the current of the inductor is linearly rising when rising to When a certain value is reached, when this threshold is reached, the current is turned off, and the next cycle is triggered by the trigger circuit. The output is generally smoothed without an electrolytic capacitor. The output current waveform is a plurality of trapezoids, that is, a wave current. A current limiting power supply, but manufacturers generally refer to it as a constant current power supply.
E. switching power supply constant current LED lamp power supply: When the output voltage is a little higher, or lower, a comparison voltage is generated. After amplification, the PWM signal is controlled, so this control method can control the voltage very accurately. This kind of control method requires a reference. The reference signal is usually a triode. This is the reference temperature drift. You can also use the conduction value of the diode 1V as the reference. If you think it is not very high, you can use it. Operational amplifier plus TL431 as the reference, if the reference is accurate, the op amp amplification is large enough, then it is very accurate, to control the PWM, although the circuit is complex, but the constant current power supply constant current accuracy is still very high. In addition, the output must be added with electrolytic capacitor filtering, so that the output is smooth DC, because the pulse can not be sampled.
F. LED light source with Transformer: Switching power supply chip with integrated MOSFET plus high frequency transformer, high power factor, moderate cost and good reliability, it is an ideal choice for led light power supply. The cost of the inductor is very low, but the load capacity is not good, and the adjustment sensitivity is not flexible.
Consider heat dissipation again, because the power supply is generally placed inside the lamp, and the heat is the biggest cause of LED light decay, so the heat is as small as possible and the efficiency is high. Since the power supply volume can be made smaller now, the T8 one meter long LED fluorescent lamp can use two power sources, one at each end, so that the heat is not concentrated in one place.
In summary, there are many options for the power supply of LED lights. We believe that with the advancement of technology and the choice of the market, there are only a few programs that can be mass-produced, and only those that meet the trend of intelligent, diversified and artistic LED lights. The product will be the final product, and those who consider it for the user are the ultimate winners, rather than disrupting the market with low-priced and inferior products.