Blinded by the Light

Have you ever been blinded by viewing your phone’s bright display at night?  Or been unable to sleep on a plane because of the amount of light coming from your neighbor’s laptop screen?  If only dimming were used, then you could read your phone at night without having to wait for your eyesight to recover as well as get to sleep on the plane without having to wait for your neighbor’s laptop battery to die.

Dimming is a standard feature on most LED drivers to reduce the light output in order to adapt the display’s brightness to varying ambient light conditions as well as to save battery life. Due to the many dimming inputs available in modern systems, from analog voltages to PWM signals to simply a single digital signal, numerous dimming circuits and techniques need to be used to interface each type of dimming signal with the particular type of LED driver being used. This often requires a significant number of external circuits, which takes time to design, as well as cost and space in the final product. One example of such circuits is here.

Certain LED drivers are optimized to accept one or more dimming methods with minimal or no extra circuits. For example, here is an LED driver that efficiently dims with just the turn of a potentiometer, an analog input signal. The same technique could be used on this LED driver or a PWM signal may be directly used, with no extra components needed.

Which dimming techniques have you found easiest to work with?

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