Diodes AL8807B - Manual (Page 11)

AL88070B
Document number: DS36191 Rev. 1 - 2
11 of 18
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March 2014
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AL8807B
Applications Information
(cont.)
Figures 35 and 36 show the PWM dimming performance of the AL8807B with a range of PWM frequencies with a nominal switching frequency of
530kHz.
Figure 35 PWM Dimming at 530kHz nominal switching frequency
Looking at difference between duty cycle and percentage of full scale LED current yields a “Linearity Error”:
Figure 36 PWM Dimming Non-Linearity at 530kHz nominal switching frequency
The accuracy of the PWM dimming is affected by both the PWM frequency and also the switching frequency of the AL8807B. For best
accuracy/resolution the switching frequency should be increased while the PWM frequency should be reduced.
The CTRL 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.