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LED System Driver ICs

ICLS6x Series

Functional Description

Data Sheet

Version 1.0, 2011-05-19

3.6

Control Unit

The Control Unit contains the functions for the Auto Restart and Floating Load Protection (FLP) modes. The Auto

Restart mode is combined with an adjustable blanking window, which varies according to the value of the external

soft start capacitor. The IC avoids entering into either of these two modes accidentally by means of this adjustable

blanking window. The window also provides a certain time during which overload detection is delayed. This delay

is useful for applications that normally work with a low current and occasionally require a short duration of high

current.

3.6.1

Adjustable Blanking Window

VSoftS swings between 3.2 V and 3.6 V after the LED drive has settled and S2 is on while S3 is off. This behavior

is due to the frequency jittering function that makes use of the soft start pin. If overload occurs, VFB exceeds 4.5 V.

The Auto Restart mode cannot be entered as the gate G5 is still blocked by the comparator C3. However, after

VFB has exceeded 4.5 V, the switch S2 is opened and S3 is closed. The external soft start capacitor can then be

further charged by the integrated pull-up resistor RSoftS through the switch S3. The comparator C3 releases the

gate G5 once VSoftS has exceeded 4.0 V. This means that Auto Restart mode cannot be entered during the

charging time of the external capacitor CSoftS.

Figure 15

Adjustable blanking window

4.0V

4.5V

3.0V

Control Unit

Auto

Restart

Mode

RSoftS

SoftS

Frequency

Jitter

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