How to prevent flicker caused by burst dimming

The DS3881 and DS3882 CCFL controllers use both analog lamp-current amplitude modulation and digital PWM burst-dimming techniques to achieve a high dimming ratio. These controllers are typically used in used in automotive, industrial and avonic applications to backlight LCD panels requiring a high dimming ratio.

Digital PWM burst dimming can cause a problem at very low dimming levels unless an external PWM signal, synchronized to the lamp clock, is used to control the width of the burst-dimming period. If that PWM burst-dimming signal is generated either from the DS3881/DS3882's internal oscillator or from an external oscillator, which are asynchronous to the lamp clock, then visible flicker can appear on the LCD panel at very low brightness levels.

This application note describes how to eliminate the flicker.

View the PDF document for more information.