AL8806

Document number: DS35144 Rev. 5 - 2

8 of 15

www.diodes.com

July 2013

© Diodes Incorporated

AL8806

PWM Dimming

LED current can be adjusted digitally, by applying a low frequency Pulse Width Modulated (PWM) logic signal to the CTRL pin to turn the device on

and off. This will produce an average output current proportional to the duty cycle of the control signal. In particular, a PWM signal with a max

achieve this resolution the PWM frequency has to be lower than 500Hz, however higher dimming frequencies can be used - at the expense of

dimming dynamic range and accuracy.

Typically, for a PWM frequency of 500Hz the accuracy is better than 1% for PWM ranging from 1% to 100%.

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Figure 2 PWM Dimming at 500Hz

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Figure 3 Low Duty Cycle PWM Dimming at 500Hz

The PWM pin is designed to be driven by both 3.3V and 5V logic levels directly from a logic output with either an open drain output or push-pull

output stage.