DocID026965 Rev 2

19/26

ALED6001

Device description

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Figure 10. Differential feedback reference voltage vs. ADIM pin voltage

In case a fixed output (LED) current is needed or simple PWM dimming is used, the ADIM

pin must be connected to the central tap of a resistor divider (supplied by the LDO3 pin) for

the desired LED current level. Because of the best LED current accuracy overtemperature

is obtained at full scale, a voltage higher than 1.2 V should be applied at the ADIM pin in

case the analog dimming is not needed.

If an analog dimming control is required, the voltage at the ADIM pin can be changed

runtime within its functional range. A simple way to perform an analog dimming is easily

achieved by extracting the average value of a PWM signal through a simple RC low-pass

filter (Figure 10).

Figure 11. Simple ADIM pin voltage control through a filtered PWM signal

If the voltage at the ADIM pin is lower than 240 mV, both the PWMO and GATE pins are

forced low and the boost converter is temporary disabled. As soon as the ADIM pin voltage

is driven inside the operating range, normal operation is resumed.