The LED driving power supply is a voltage converter that converts the power supply into a specific voltage and current to drive the LED to emit light. Usually, the input of the LED driving power source includes high-voltage power frequency alternating current (ie, mains), low-voltage direct current, high-voltage direct current, low voltage high. Frequency communication (such as the output of an electronic transformer). The output of the LED driver is mostly a constant current source that changes the voltage as the LED's forward voltage drop changes. Since the performance and conversion efficiency of LED power supplies of different specifications are different, it is necessary to select a suitable and efficient LED dedicated power supply to truly reveal the high-performance characteristics of the LED light source. Because the low-efficiency LED power supply itself needs to consume a large amount of power, it is impossible to highlight the energy-saving characteristics of the LED in the process of supplying power to the LED. In short, the LED power supply has an important role in the stability, energy saving and long life of the LED. What are the classifications of LED power supplies? First, the LED power supply can be divided into two categories according to the driving method: A. Voltage regulation: 1. After the voltage regulator circuit determines various parameters, the output is a fixed voltage, and the output current changes with the increase or decrease of the load. 2. Although the voltage regulator circuit is not afraid of the load open circuit, it is forbidden to completely short the load. 3. The voltage change after rectification will affect the brightness of the LED. 4, to make each string with the voltage regulator circuit to drive the LED display brightness uniform, you need to add the appropriate resistance before you can B. Constant current type: 1, constant current drive circuit to drive LED is very ideal, the disadvantage is that the price is higher 2. Although the constant current circuit is not afraid of load short circuit, it is forbidden to completely open the load. 3. The current output by the constant current drive circuit is constant, and the output DC voltage varies within a certain range depending on the magnitude of the load resistance. 4, to limit the number of LEDs used, because it has the maximum withstand current and voltage values Second, LED power supply can be divided into six categories according to the circuit structure: 1. Conventional transformer step-down: The advantage of this kind of power supply is that it is small in size. The disadvantage is that the weight is heavy and the power supply efficiency is very low. Generally, it is 45%~60%. Because the reliability is not high, it is rarely used. 2, capacitor step-down: The LED power supply in this way is easily affected by the voltage fluctuation of the power grid, and the power supply efficiency is low. It is not suitable for the LED to be used when flashing, because the circuit is stepped down by the capacitor, and when the flashing is used, the instantaneous current through the LED is due to the charge and discharge. Great, easy to damage the chip. 3, electronic transformer step-down: The insufficiency of this power structure is that the conversion efficiency is low, the voltage range is narrow, generally 180~240V, and the ripple interference is large. 4, resistance buck: This type of power supply is very inefficient and the system is less reliable. Because the circuit is stepped down by the resistor, it is greatly interfered by the change of the grid voltage, it is not easy to make a regulated power supply, and the step-down resistor itself consumes a large part of the energy. 5, RCC step-down switching power supply: The advantage of this type of LED power supply is that the voltage regulation range is relatively wide and the power supply efficiency is relatively high, generally 70%~80%, and the application is wide. The disadvantages are mainly that the switching frequency is not easy to control, the load voltage ripple coefficient is large, and the load adaptability of the abnormal situation is poor. 6, PWM control type switching power supply: At present, the LED power supply designed by the PWM control method is ideal because the output voltage or current of the switching power supply is stable. The power conversion efficiency is extremely high, generally up to 80%~90%, and the output voltage and current are very stable. The LED power supply of this mode is mainly composed of four parts: input rectification filtering part, output rectification filtering part, PWM The voltage regulation control part and the switching energy conversion part. Moreover, this circuit has perfect protection measures and is a highly reliable power supply.
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