The difference between LED driver power supply and LED power supply

The difference between LED driver power supply and LED power supply

The difference between LED driver power and LED power supply? In fact, there is no difference in essence, but the names are different. There are many names for LED power supplies. Ballasts, LED power supplies, and LED drive power supplies are actually all power supplies suitable for LED lamps in essence. Gongxin Technology Power Supply will give you a detailed answer.

When designing LED lighting fixtures, it is necessary to consider the selection of a suitable LED driving power supply. The quality of the LED  driving power directly determines the quality of the LED  lamps, and the connection method of the LED should be considered at the same time. At present, the connection methods of LEDs include series, parallel, hybrid, and cross-array. The design of the LED light board is to carry out a reasonable matching design (connecting the LEDs together in a reasonable way) according to the actual design of the product to ensure the normal operation of the LED light board. The forward voltage range of white LED lamp beads is generally 3.0~3.6 V, the power is 1W, 3W, and the working current is 350mA, 700mA (the actual working current is 300mA, 600mA). However, for LED fluorescent lamps, LED downlights and other lighting fixtures, multiple small and medium-power LED lamp beads are combined in series and parallel, and each LED has a working current of 45~120 mA. Usually a larger number of LED lamp beads are required to match to produce uniform brightness. At present, there are also COB surface light sources, the number of strings is 12, and the current is different, ranging from 3W to 60W.

Note:

      ①The arrangement of the LEDs and the specification of the LED light source determine the basic driver requirements. The main function of the LED driver power supply is to limit the current flowing through the LED under a certain range of operating conditions, no matter how the input and output voltages change.

      ②The VF value of the LED lamp bead is related to the luminous color and the working temperature of the LED. The VF value of the LED is also different at different temperatures. The higher the ambient temperature, the smaller the VF value, and the VF value is inversely proportional to the ambient temperature.

      ③The VF value of LED lamp beads is different from the manufacturer. The VF value of the same package LED is different from different manufacturers.

      To design an LED drive circuit (power supply), it is necessary to master the working principle of LED lamp beads. The brightness of LED lamp beads is mainly related to VF and IF. Small changes in VF can cause large changes in IF, and thus large changes in brightness. To keep the LED in the best brightness state, a constant current source is required to drive it. The LED drive circuit is a power conversion circuit, but it outputs a constant current instead of a constant voltage. In any case, a constant and average current should be output, and the ripple current should be controlled within a certain range.

      When choosing an LED drive power supply, it is necessary to determine the size of the VF value under the working environment temperature of the LED lamp bead, and select the appropriate output voltage (working voltage) working range of the drive power supply according to the series-parallel relationship of the number of connected LEDs. The total voltage obtained by the maximum VF value of the LED × the number of LEDs in series = the maximum operating voltage of the LED. The maximum value of its working voltage is more than 5V lower than the maximum output voltage of the power supply. The total voltage obtained by the minimum VF value of the LED × the number of LEDs in series = the minimum value of the LED operating voltage, and the minimum value of the operating voltage is more than 5V higher than the minimum output voltage of the power supply. That is, the operating voltage range of the LED drive power supply = (the total LED operating voltage (3.2V × the number of LEDs in series) + 5V ~ the total operating voltage of the LED (3.2V × the number of LEDs in series) -5V). The total working power of the LED drive power is about 90% of the power selected for it.

Note:

      ①VF is the forward voltage drop of the LED lamp bead, and IF is the forward current of the LED lamp bead. The maximum output voltage of the LED drive power supply = power supply ÷ output current, and the minimum output voltage = the maximum output voltage × 60%.

      ②The whole light efficiency of LED lamps = (LED light source light efficiency × light transmittance × heat loss × driving power conversion efficiency).

      ③ When choosing an LED drive power supply, a high-efficiency drive power supply should be selected. Such a drive power supply generates less heat and has a long working life. At present, the efficiency of LED drive power supply below 10W is generally above 80%. LED drive power above 10W, its efficiency is generally above 90%.

      White LEDs need to be well applied and have high efficiency. It is necessary to use a suitable LED drive power supply to meet the LED work requirements. The requirements for the LED driver power supply are as follows:

      ①LED drive power supply is a special power supply for LED power supply, which has the characteristics of simple circuit structure, small size and high conversion efficiency.

      ②The output electrical parameters of the LED drive power supply (ie output current, output voltage) match the parameters of the LED lamp beads to meet the requirements of the LED lamps and lanterns. It must have high constant current precision control and appropriate voltage limiting function.

Note:

When the LED drive power supply has multiple outputs, the output of each channel must be independently controllable.

      ③The LED drive power has a dimming function with good linearity to meet the dimming requirements of different LED applications.

      ④LED drive power supply can protect its power supply itself, LED and users accordingly when the LED is open, short-circuited, or the drive circuit is faulty, and will not cause danger.

      ⑤ When the LED drive power supply works, it should meet the relevant electromagnetic compatibility (EMC, EMI) requirements.

      According to the application requirements of different occasions, the LED driving power supply can adopt three circuits: constant voltage (CV), constant current (CC), and constant current and constant voltage (CCCV).

(1) Constant flow (CC)

      ①The output current of the constant current drive circuit is constant, but the output DC voltage varies within a certain range with the difference of the load resistance value. The smaller the load resistance, the lower the output voltage; the larger the load resistance, the higher the output voltage.

      ②The constant current power supply is not afraid of short circuit of the load, but it is strictly forbidden to open the load completely.

      ③It is ideal to drive the LED light source with a constant current drive power supply, but the price is relatively high.

      ④ Pay attention to the maximum withstand voltage of the power supply, which limits the number of LED light sources used.

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