The VF voltage of LED light sources for lighting is very low, generally 2.75~3.8V, and IF is generally 15~ 1,400 mA. Therefore, the output voltage of the LED drive IC is VFxN or VFx1, IF the constant current is maintained at 15~ 1,400 mA. There are two kinds of LED light sources for LED lamps: small power (IF 15~20mA) and large power (IF greater than 200mA). Small power LED is used for making LED fluorescent lamps, decorative lights, grille lights. High-power LED is used to do household lights, spotlights, underwater lights, wall washing lights, street lamps, tunnel lights, car work lights, etc. The power LED light source is a device driven by low voltage and high current. Its luminous intensity is determined by the current flowing through the LED. Excessive current will cause LED light attenuation, and too small current will affect LED light intensity. Therefore, the DRIVE of LED needs to provide a constant current power supply, so as to ensure the safety of high-power LED and achieve the ideal luminous intensity. In the field of LED lighting, in order to reflect the characteristics of LED lamp energy and long life, the right choice of LED drive IC is very important. Without a good driver IC match, the advantages of LED lighting cannot be reflected.

Low voltage drive chip requirements for LED lamps
1. The nominal input voltage range of the driver chip shall meet dc 8~40V to cover a wide range of application needs. The withstand voltage should be greater than 45V. When the input is ac 12V or 24V, the output voltage of a simple bridge rectifier will fluctuate with the grid voltage, especially if the voltage is too high, the output DC voltage will also be too high. If the drive IC does not have a wide input voltage range, it will often be broken down when the grid voltage rises, thus burning out the LED light source.
2. The nominal output current of the driver chip shall be greater than 1.2~ 1.5a. As LED light source for lighting, the nominal working current of LED light source of 1W power is 350mA, and that of LED light source of 3W power is 700mA. Large power LED light sources need more current, so the drive IC selected for LED lighting lamps must have sufficient current output, and the design of the product must also make the drive IC work in the best working area of 70-90% of the output at full load. The drive IC with full load output current has poor heat dissipation in the narrow space of the lamp, which easily leads to fatigue and early failure of the lamp.
3. The output current of the driver chip must be kept constant, so that the LED can shine steadily without blinking. When the same batch of driver chips are used under the same conditions, the output current should be as consistent as possible, that is, the discreteness should be small, so as to ensure the efficiency and order when they are produced in the mass automated production line. For the driver chip with a certain dispersion of output current, it must be sorted before leaving the factory or putting into the production line. The resistance value of the current setting resistance on the PCB board should be adjusted to make the constant current driving plate of LED lamps produce consistent luminance to the same LED light source, so as to maintain the consistency of the final product.

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