DocID026965 Rev 2

13/26

ALED6001

Device description

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Figure 4. Turn on and turn off waveforms

Suddenly after the pulse detection at the PWMI pin, an internal timer is enabled and

cleared. The timer starts counting down on every subsequent falling edge. If the PWMI pin is

held low for more than 10 ms (typ.), the timer is allowed to expire and the ALED6001

automatically turns off minimizing the current consumption.

The start-up time, defined as the delay between the rising edge at the PWMI pin and the first

pulse at the GATE pin, clearly depends on the bypass capacitors connected on both LDO3

and VDR pins. With a typical 1 µF MLCC for both pins, the start-up time is in the order of

100 µs.

7.2.2

Boost controller operation

The boost controller of the ALED6001 device is based on peak current mode control

architecture and can easily support boost, floating buck-boost and SEPIC topologies. The

switching frequency of the converter is set through the FSW pin (external clock source or

setting resistor toward ground) while the switching duty cycle is modulated by the control

loop in order to keep the output (LED) current constant. As a consequence, the output

voltage of the boost converter is determined by the LED string.