| As a main part of the automotive electronic system, driver of the automotive LED has occupied a space in the automotive electronic system. Driver of the automotive current regulative LED with stable output is the premise of the whole system's performance. As the LED driver's output depends on its internal circuit and the LED's characteristic, so we begin with the LED luminescence principle in this paper and the principle is detailed analyzed here. Then we designed the corresponding LED driver to meet the demands of the automotive electronic environment. Nowadays, the research and design of the automotive LED driver has been a hotspot in the market of the power management chip.Our automotive LED driver is described in the paper. The circuit uses the universal device and has a simple architecture. It fulfills a high-performance automotive LED constant current driver's function and it can be applied in all sorts of ultrahigh brightness LED lighting systems. The automotive LED driver can produce constant current which has a high accuracy, small ripple and low noise.The chip also features the function of over temperature protection, over current limiting and +5V regulator output. The driver can be applied in a 12V automotive electronic system.In this paper, we put emphasis on the designing method of LED driver's protecting circuit, its internal designing flow and the results of our design. The PWM dimming controlling, design of the Trimming bandgap reference and linear regulator are also detailed described here.Finally, the whole chip's simulation is done in Cadence specture, and the simulation results show that the chip can also source a 2mA light load at the V5 pin when the output current reaches up to 350mA. In addition, the protection measures can play a very good role in the protecting the chip; meanwhile, the dimming function can be realized in Analog way or by the external PWM signal. The whole chip simulation results show that our chip has met the established requirements. |
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