Car LED lighting design

Light-emitting diode ( 领导) Lighting for novelty, comfort, and open a new land users to customize. These design opportunities in the burgeoning LED in the application level and speed of the car. When the LED used in the car, the front and the rear lighting, there are several methods and design techniques to choose from.

for automotive LED, its against vibration, long life, energy efficient and to fine control features such as the light source is the key factor. Compared with incandescent light bulbs, LED is not sensitive to mechanical shock, but need to drive circuit. In general, auto electrical power supply system for lead-acid battery power source, the battery driven by engine through mechanical way ac generator/charging voltage regulator. Such a system is suitable for the old incandescent bulbs, but not suitable for the LED. In order to make the LED to achieve the best performance, a precision constant current source of current.

for the correct drive leds, it is necessary to control current, and has nothing to do with the voltage. Basic depends on the light output current rather than voltage. In theory, every electronic convert photons, and escape out of the LED a fixed proportion of photons as we see the light.

with constant voltage, simply a resistor can achieve a quality plan. It should be noted that when the LED and resistor simple concatenated together, the LED is self-adjusting itself to a certain extent. If the temperature increases, the efficiency and brightness of the LED are reduced, and prior to the pressure drop decreases at the same time. Reduce the forward voltage drop and cause current is added, thus slightly offset caused by temperature rise the brightness of the decline. As long as the battery voltage constant, series resistance scheme is enough to meet the requirements of the computer and instrument application. But auto industry mandatory equipment need to be able to meet the batteries in 8 v to 18 v to change, and also can bear 80 v peak. In addition, highlighting the LED will produce large amounts of heat on the resistance. Thus makes the thermal design more difficult.

a better but it is not the best alternative is to use a dc - Dc voltage converter to generate a suitable and stable voltage and then combine this with a resistor. If you have a computer or other electronic equipment power supply dc - Dc converter, the scheme is feasible; In addition, this method is probably the most commonly used method drive leds.

but adopt a job has nothing to do with the voltage of constant current drive leds is a better solution. Energy consumption and energy conversion are two basic types of constant current type.

linear voltage constant current device is an example of energy consumption constant current devices. For a given current, constant current device on both ends of the pressure drop represents energy consumption be burned off. Another case is a constant flow of energy conversion, it attempts to store the energy difference between different level.

describe the equation of the used energy conversion is one of the basic law of thermodynamics

the input power = output power with W =

v. I given ( A given) , replace the W:

Vin, Iin = Vout, Iout + ( 100 - X % efficiency) W heater ( Fever)

if the leds of the forward voltage as Vout, as the required current Iout, they will get general equation describing the LED driver. Leo

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