LED is recognised as a fourth generation green light source. It is a robust cold light source. It has the advantages of high efficiency, long life, safety and environmental protection, small size, high reliability and fast response time. Currently, the same lighting effect is achieved. The power consumption of LED is about 1/10 of incandescent and 1/2 of fluorescent. many countries and regions have introduced various policies to support the development of the LED industry, making the industry an important part of the country's key industries and breeding huge business opportunities. the LED driver circuit is very important for LEDs, and LED dimming control can save energy. The driving and dimming of high brightness white LEDs has been a hot topic in recent years.What is a LED Driver?
Led driver changes the power supply to a specific voltage current to drive the LED voltage converter. In general, the input of the LED driver includes the high voltage power frequency AC (i.e., the city electricity), the low voltage DC, the high voltage DC, the low voltage and high frequency AC (such as the output of the electronic transformer). The output of LED driver power is mostly a constant current source that can change voltage with the change of LED forward voltage drop. The core components of LED power supply include switch controller, inductor, switch component (MOSFET), feedback resistor, input filter device, output filter and so on. According to the requirements of different occasions, there must be input over-voltage protection circuit, input under-voltage protection circuit, LED open circuit protection, over-current protection circuit and so on.
The common market led lamp driver is divided into two kinds according to the driving mode. One is constant current drive. The characteristic of constant current drive is that the output current is constant. The output voltage is changed in one range. So we often see that the driving shell is marked out (output: DC**V - **V * * * mA+-5%) in the market. This means that the output voltage is in one of the output voltages. The range, the current is how many ma.
A. The output current of the LED driver constant current circuit is constant, but the output DC voltage varies in a certain range with the different size of the load. The load resistance is small, the output voltage is low, the greater the load resistance is, the higher the output voltage is.
B.Constant current circuit is not afraid of load short circuit, but it is strictly forbidden to load fully open.
C.The constant current drive circuit is ideal for driving LED, but relatively speaking, the price is higher.
D.Attention should be paid to the maximum withstand current and voltage used, which limits the number of LED used.
And the other is the constant voltage drive. The characteristic of the constant voltage driving is that the output voltage is fixed, the current is within the maximum value with the change of the lamps and lanterns. In the case, the shell usually indicates (output:DC**V **A) is the voltage of the output fixed volt, the maximum output current is how many.Led market common is the output 5V, 12V, 24V and so on.
A.When the parameters in the voltage stabilizing circuit are determined, the output voltage is fixed, while the output current changes with the increase or decrease of the load.
B.The voltage stabilizing circuit is not afraid of load opening, but it is strictly forbidden to load short circuit completely.
C.The LED is driven by a regulated drive circuit. Each string needs a proper resistor to make the average brightness of each string LED average.
D.The brightness will be affected by the voltage changes that are rectified.