As LEDs improve in brightness, they are offering many benefits in the automotive world. Having hung on a step ladder in an icy truck lot while changing filament bulbs on over the road trailers in a Siberiacuse winter, I understand the advantages all too well. The filament bulbs were subject to failure due to road vibrations as well as fusing during the rapid temperature changes when applying current during a period of extreme cold. Other advantages include color control as well as light dispersion. LEDs don’t have to heat up either so the light is immediate.
Along with the LEDs, there has been a large entrance into the LED driver market as well. The basics of the drivers are to control the LED current to maintain a certain brightness. I said current not voltage for the recent distribution Applications Engineer who couldn’t get it right. In reality, the current keeps the LED happy for longevity as well as color by setting the current level. The brightness is then adjusted using pulse width modulation or PWM. This is nothing more than an averaging pulse that controls the light ON time or duty cycle in relation to a total period or frequency. The frequency is set to a level so that it doesn’t appear to be flashing to the human eye.
There are many ways to classify automotive LED lights and drivers. Texas Instruments classifies their drivers by location by grouping them into Exterior Lighting, Interior Lighting, and LDC backlighting, infotainment, and cluster. Allegro Microsystems has an informative diagram for their automotive LED driver products.
There are other ways to look at the automotive LED market. Classifications can include illumination, marking and warning lights, backlighting, and theatrical or accessory based. Among these markets are both OEM and aftermarket opportunities.
The basic automotive exterior lights include headlights, daytime running lights (DRL), and the marker and indicator lights such as tail lights, signal lights,