LED System Driver ICs

ICLS6x Series

Functional Description

Data Sheet

13

Version 1.0, 2011-05-19

3

Functional Description

All values used in the functional description are typical values. When calculating the worst cases, the

minimium/maximum values listed in Electrical Characteristics on page 24 have to be considered.

3.1

Introduction

For ICLS6x Series controllers, a high voltage startup cell is integrated into the system IC, which is switched off

once the undervoltage lockout-on threshold of 18 V is exceeded. This startup cell is part of the integrated depletion

CoolMOS™. The external startup resistor is no longer necessary as the startup cell is connected to the drain,

resulting in reduced power losses. This increases the efficiency under light load conditions drastically.

The soft start capacitor is also used for providing an adjustable blanking window for high load jumps. The overload

detection function is disabled during this window. With this concept, no further external components are necessary

to adjust the blanking window.

An Auto Restart mode is implemented in the IC to reduce the average power conversion in the event of malfunction

or unsafe operating conditions in the LED drives. This feature increases the system’s robustness and safety, which

would otherwise lead to a destruction of the LED drive. Once the malfunction is corrected, normal operation is

automatically initiated after the next startup phase.

Together with the soft start capacitor, the feedback can also sense a missing load, which leads to rising output

and auxiliary voltages. This triggers the Floating Load Protection (FLP) mode. When feedback falls below 1.35 V,

the Soft Start voltage begins to rise up to a threshold of 4 V (depends on the C4 value) and the IC is switched into

FLP mode.

The precise internal peak current limitation reduces the costs for the transformer and the secondary diode. The

influence of the change in the input voltage on the power limitation can be avoided together with the integrated

Propagation Delay Compensation circuit. Consequently, the maximum power is practically independent of the

input voltage required for wide range LED drives. There is no need for additional oversizing of the LED drives –

e.g., for the transformer or the secondary diode.