In the LED application products, LED must be a certain circuit design. Under normal circumstances, according to different drive voltage to choose different combinations of series and parallel, LED Clothing Light at the same time should fully understand the LED's electrical and thermal characteristics, to ensure long-term reliable LED products. In order to reduce the single-lamp fault in the series line, LED Clothing Light the risk to the whole circuit should be avoided by the number of series-connected LEDs in series. In single lamp applications, try to use parallel mode. Parallel mode LED lights try to use constant voltage power supply mode.
LED lighting system in the design, we must consider the selection of suitable LED driver power supply, taking into account the LED connection. The current LED connection in series, LED Clothing Light parallel, hybrid, cross array. Design is based on the actual design of the product, the design of a reasonable match (using a reasonable way to connect the LED), in order to ensure the normal operation of the LED. White LED forward voltage range is generally 2.8 ~ 3.5 V, power 0.5W, 1W, the operating current of 150mA, 350mA. However, LED fluorescent lamp, downlight lighting is a combination of multiple small and medium power LED through the series and parallel mode, and its operating current is 20 ~ 60mA. Usually require a large number of LED matching, in order to produce uniform brightness.
The arrangement of the LEDs and the specifications of the LED light source determine the basic drive requirements. The main function of the LED driver is to limit the current through the LED under certain operating conditions, regardless of the input and output voltage.
The VF value of LED lamp beads is related to the luminescent color. At the same time, the VF value of LEDs with different temperatures is also related to the working temperature of LED. LED Clothing Light The higher the ambient temperature is, the smaller the VF value is and the VF value is inversely proportional to the ambient temperature.
The VF value of LED lamp beads is different from the manufacturer, with the same manufacturer of different LED, the VF value is not the same.
To design LED driver circuit, to master the working principle of LED. The brightness of LED is mainly related to VF and IF. A small change in VF causes a large change in IF, LED Clothing Light causing a large change in brightness. To keep the LED in optimal brightness state, LED Clothing Light a constant current source is required to drive it. LED driver circuit is a power conversion circuit, but the output is a constant current rather than a constant voltage. In any case, should be output constant and average current, ripple current to be controlled within a certain range.
Select the LED driver power supply, LED lights to determine the working environment temperature under the VF value, according to the LED string and the relationship between the output voltage to select the scope of work. LED Clothing Light Its output voltage range, the maximum VF with LED × number of series LED total voltage, the value of the power output than the maximum voltage of 5V or more. LED Clothing Light With the minimum VF LED value × the number of total LED number derived from the total voltage, the value of the minimum output voltage than the power supply 5V above. LED drive power for the power of about 90% of the total power.