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How To Choose The Right LED Headlight Driving Scheme

Jun 15, 2020

   Advanced LED headlight technology is not limited to the lamp itself, it has developed into an intelligent technology combined with various electronic technologies. There are thousands of LED headlight solutions. How to choose a high-performance headlight chip solution? In this article, we will discuss with you.

  1. The development process of automobile headlights:

  First of all, let's take a look at the development process of automobile headlights: kerosene lamp->acetylene lamp->incandescent lamp->halogen lamp->xenon headlight->LED headlight->laser headlight. Although xenon headlights are still the most mainstream car headlight configuration today, LED headlights have begun to enter people's vision more and more, and the application speed is very fast.

  Second, the internal functional composition of the headlights

  The headlight is actually composed of many functions, including high beam function, low beam function, daytime running light function, turn signal function and corner light function and so on. Then the LED headlights, as the name suggests, means that each function is composed of LEDs.

  3. How to choose the right LED headlight driver chip?

  First of all, we must ensure that the current driving the LED is constant; secondly, the power of the LED headlight is relatively large, especially the high beam and low beam, the current of the LED is mostly around 1A, and the output voltage is determined by the number of customer LEDs and the Vf value . Based on the above two reasons, we must consider the design of a constant current DC lamp driver that can output a larger power.

  If the customer chooses to independently develop an entire headlight, and if each function uses a DC circuit to drive, this will not only increase the cost of peripheral devices (such as inductance, anti-reverse, freewheeling diode, mosfet, etc.), but also not conducive to Customers carry out extension and post-maintenance of platform solutions. The following introduces a headlight solution, which is suitable for customers to carry out platform management and reduce costs.

  Headlight solution introduction

  1. Block diagram

  2. Components of the program:

  1) mcu: With the diversification of car light effects, mcu is becoming more and more popular, and mcu can be used to control lighting logic.

  2) Lamp driver: first boost boost, then multi-channel buck constant current lamp driver solution. Choose the appropriate boost and buck according to the specific LED load size. If the customer's load is relatively small, it is recommended to integrate a single-phase boost+2 buck and integrated lamp driver. If the load is large and there are many types of lamps, you can connect the lamp drivers in parallel. At the same time, customers can also consider multi-phase boost and multi-channel buck solutions. We can recommend 2-phase/3-phase/4-phase boost, and 1-way/2-way/3-way buck.

 3) SBC: integrated ldo, CAN transceiver and watchdog in one. Compared with discrete devices, in addition to meeting the basic needs of customers, it can also reduce PCB area and improve system reliability.

  4) Peripheral: inductor, freewheeling diode, mosfet, etc.

  5) Anti-reverse: If the customer's load is relatively large, the input current of the power supply may be relatively large. If you choose to use a small Pson anti-reverse of Rdson, the loss will be reduced. If the input current is not large, you can consider using a diode to prevent reverse.