Compared with the vehicle's interior and exterior lighting solutions, LED lighting has many advantages such as higher performance, longer life, lower cost, this way of lighting and automotive lighting aesthetics and performance. However, want a car battery-powered LED requires a DC / DC converter regulator a constant LED current, and to protect the LED from the car battery changes a dramatic effect. This conversion should be based on the series of the function of the LED Spotlight 30W contained in the number of LED's and LED type as well as headlamps, taillights and signal lights, interior reading lights, dashboard, or entertainment display lighting applications optimized, should pay attention to:
(1) Architecture - the relationship between the LED voltage and battery voltage buck, boost or buck-boost architecture, the choice of architecture to be able to maintain LED current controlling the entire battery voltage range.
2 dimming must be - a large proportion of led driver 120w dimming in the brightness level to maintain the same color characteristics, and not visible to the naked eye and downs or oscillation.
(3) efficiency - battery power consumption in the non-running state power loss, but also in the car this heat has been great pressure on the environment, the consumption of electricity is transformed into heat.
Drive a single LED
Interior white headlights and make-up lights may use one or two 3W LED, each LED to produce 75-100 lumens of brightness. Typical LED forward voltage range of 3V to 4.5V, the maximum current of 1A to 1.5A, for example, Lumileds' Luxeon III Star. The most simple LED driver design using a buck regulator, directly to the car battery to drive a single LED Floodlight 80W.
Shown in Figure 1, with a dimming function single LED Power Supply interior lighting circuit. The typical car battery operating voltage range of 9V to 16V (typical value of 12V). An electricity consumption of the battery before the car starts, the voltage perhaps down to 9V, alternator charging the car starts to revert to its voltage up to 14.4V when the cold start, the battery voltage may drop to 4V, then The only key to the electronic circuit to work.
Long cable between the different locations as well as electronic noise environment makes the car battery and chassis, there is always a high-voltage spikes. Select the switching regulator for automotive design, 36V transients that must be considered, usually through a simple protection diodes or filters to deal with high voltage spikes. converter integrated circuit used in Figure 1 is a high-voltage, high current buck LED converter, the component with a wide PWM dimming ratio can drive one or more LED Flood light 10W current up to 1A. wide input voltage range of 4V to 36V, the LED drive directly to the car battery, while providing a constant LED current, and its step-down architecture and adjustable broadband range, allowing the use of small, low-cost, high-temperature coefficient of ceramic capacitors, Low Ripple LED current.