Requirements of LED lamps for low voltage drive chips

【China Building Materials Network] LED lighting has developed rapidly in the near future. LED has been widely recognized as a green and clean light source. LED light source has long service life, energy saving, simple and convenient application and low use cost, so it will be widely used in home lighting. According to survey statistics, the annual shipment of home lighting lamp holders is about 50 billion. 1. The nominal input voltage range of the driver chip shall meet DC8- 40 V, in order to cover the application surface, the pressure resistance is better if it can be greater than 45 V; When AC12V or 24V is input, the output voltage of a simple bridge rectifier will fluctuate with the grid voltage, especially when the voltage is too high, the output DC voltage will also be too high. If the driving IC cannot adapt to a wide voltage range, it is often broken down when the grid voltage rises, and the LED light source is burned. 2. The nominal output current of the drive chip is required to be greater than 1. 2-1. 5A, as an LED light source for lighting, the nominal working current of 1W power LED light source is 350mA, and that of 3W power LED light source is 700mA, high power requires larger current, so the driving IC selected for LED lighting lamps must have sufficient current output, and the driving IC must work at 70-of full negative output when designing products-A good work area of 90. Driving IC with full negative output current causes poor heat dissipation in narrow space of lamps, which is easy to fatigue and early failure. 3. The output current of the driving chip must be constant for a long time, so that the LED light source can emit light stably and the brightness will not flash; 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 that the production can be effective and orderly on large-scale automatic production lines; For the drive chip with certain discreteness of the output current, it is necessary to adjust the current setting resistance (Rs) The resistance value of the LED lamp produced by the constant current drive board is consistent with the luminous brightness of similar LED light sources and maintains the consistency of the final product. 4. The packaging of the driver chip shall be conducive to the rapid heat dissipation of the driver chip die, such as the die (Die) Directly bound to the copper plate, and a Pin is directly extended outside the package, which is convenient to directly weld on the copper foil of the PCB plate for rapid heat conduction (Figure 1). For example, on a silicon chip die similar to 4X4mm, it takes a long time to pass through 300- The current of 1000mA must have power consumption and heat generation. The physical heat dissipation structure of the chip itself is also crucial. 5. The ability of the driver chip itself to resist EMI, noise and high voltage is also related to whether the whole LED lamp product can pass smoothly.