1 LED offers many advantages for automotive lighting applications LEDs are used in a wide range of applications in automobiles, but can be easily summarized into internal and external lighting (see Figure 1). Exterior lighting is like headlights, taillights, etc. Interior lighting includes interior convenience and comfort lighting and dashboard backlighting. Figure 1: A wide range of automotive LED lighting applications There are many factors driving automotive LED lighting applications. For example, in the case of a previous lamp, the use of LED as a light source has many advantages: 1.1 Conducive to flexible or innovative design The physical size of the LEDs is small and can be used to develop extremely compact, extremely thin modules. Multi-string LED modules require smaller, simpler lens and light diffuser hardware than halogen and xenon lamps. And the light of multiple LED light sources is easier to guide, greatly reducing the impact of engineering design on the shape. 1.2 Light intensity and energy efficiency continue to increase The LED light intensity is on an extremely fast rise curve, showing a trend that the luminous flux will double every 18 to 24 months. The LED light output has exceeded the halogen lamp, and the actual LED performance of the LED will be comparable to that of the Xenon lamp. 1.3 High reliability and long life As long as the LED headlamp module is effectively thermally managed to maintain a low junction temperature and protect it from switching on/off, current spikes and battery pulses that may occur during dimming, it is expected that they will be throughout the vehicle. It is not unrealistic to continue to use it during the life cycle. 1.4 Significant energy saving LED headlamps use much less fuel/energy than other solutions. Using energy-efficient smart power technology/chips instead of general ICs that require multiple external components can be more energy efficient. Therefore, the application of LED in automotive lighting is increasing, and it is regarded as a design selling point by many automobile manufacturers. 2 Comparison of LED driver solutions for automotive lighting LEDs are widely used in automotive lighting. Different applications have different LED current requirements. Therefore, it is necessary to select a suitable LED driver solution according to specific application requirements. One of the main functions of the LED drive scheme is to stabilize the flow under a variety of operating conditions, regardless of input conditions and how the forward voltage changes. The drive solution must meet the application requirements for energy efficiency, form factor, cost and safety. At the same time, the chosen solution must be easy to use and strong enough to adapt to the strict environment of the particular application. Typical LED driver solutions in automotive applications include resistors, linear LED drivers, switch LED drivers, and innovative lighting management LED drivers. In general, depending on the amount of LED current in the application, discrete components (ie, resistors) or linear drive schemes can be used in low current applications from 20 to 200 mA; in medium current applications from 200 to 500 mA, optional Linear or switch driver solutions; in high current applications greater than 500 mA, the switch driver scheme is typically chosen. In fact, resistors are the simplest and lowest cost LED current limiting solution, but they are not “steady flowâ€, but simply when the LED forward voltage changes and the input supply voltage changes and causes a current change that causes LED brightness variation. Limit the maximum LED current. Although the cost of this solution is low, the energy efficiency is also the lowest, and there are problems such as LED screening cost and thermal runaway. CCR is a higher performance but lower cost solution than a linear driver or switch driver for low current LED lighting applications with currents less than 200 mA. CCR is inexpensive and rugged, provides constant brightness over a wide voltage range, protects the LED from overdriving when the input voltage is high, and still provides higher brightness at low battery voltages. This solution can reduce or eliminate the inventory generated by LED screening, making the total cost of the solution lower. With a maximum operating voltage of 50 V, the CCR can withstand battery load sags. CCR offers different packages such as SOD123, SOT123 and DPAK, which can operate in a severe thermal environment (125 °C), and the negative temperature coefficient characteristic protects the device itself and the LED under high ambient temperature conditions. In addition, CCR does not generate electromagnetic interference and is easy to design. 