What are the characteristics of LED driver ICs?
|LED driver ICs used to drive white LEDs account for approximately 50% of the total LED driver market. White LEDs are commonly used to backlight small displays for many battery-powered handheld portable products. However, this type of lighting application has matured and will not have a high compound annual growth rate in the next five years. For LED lighting applications, the three largest markets with a compound annual growth rate that is much higher than the handheld backlight market are: large flat panel HDTVs, automotive headlights and general lighting.|
Traditionally, LED dimming is accomplished by using a DC signal or a filtered PWM signal to regulate the forward current flowing through the LED. Reducing the LED current adjusts the LED light output density. However, a change in the forward current causes a change in the color of the LED illumination because the chromaticity of the LED varies with the current. Many applications, such as LCD HDTVs and automotive backlights, do not allow for any deviation in the LED's illumination color. Wide dimming ranges are required in these applications due to differences in ambient light and the small changes in light intensity perceived by the human eye. By using the PWM signal to control the light intensity of the LED, the LED dimming can be realized without changing the color of the light.
It is clear that LED has become the mainstream choice. However, system designers still need LED driver ICs that meet their specific design performance requirements. Therefore, LED driver ICs must be able to meet the input voltage range and the desired output voltage and current requirements of the conversion topology, providing sufficient current and voltage for many different types of LED configurations.