ZLED7030

High Current 40V LED Driver with Switch Dimming

Data Sheet

August 16, 2011

© 2011 Zentrum Mikroelektronik Dresden AG — Rev.1.2

All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without

the prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.

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The input conditions on the DIM1 and DIM2 pins set the number of current levels and the current ratio relative to

the initial average current for the dimming switch (DS) sequences as shown in Table 2.1.

Table 2.1

Dimming Configuration Options

Dimming Mode

DIM1

DIM2

Dimming Ratio K

No dimming

Floating

Floating

(100%)

1

Floating

GND

100%

1

50%

2

20%

3

100% …

2

GND

Floating

100%

1

60%

2

30%

3

100% …

3

GND

GND

100%

1

30%

2

100% …

If a normal switch is detected or if DIM1 and DIM2 are both floating, the output current goes back to the initial

state of 100% nominal average output current. Since ZLED7x30 needs to count the time for more than 2 seconds

after the switch is off during a normal switch, one capacitor (C1) equal to or greater than 220

µF is required to

keep the chip working in low quiescent current mode during this part of the off-time.

2.4

ZLED7x30 Protection Features

2.4.1

Thermal Shut-down Protection

The ZLED7x30 automatically protects itself from damage due to over-temperature conditions. If the ZLED7x30’s

thermal considerations.

2.4.2

LED Open-Load Protection

As a step-down converter, the ZLED7x30 has inherent open-load circuit protection. Since the L1 inductor is

connected in series with the LED string, the current flow is interrupted if the load is open and the LX output of the

ZLED7x30 will not be damaged. This provides an advantage over other products such as boost converters, for

which the internal switch can be damaged by back EMF forcing the drain above its breakdown voltage.