ZLED7015

1.0MHz Boost Converter with Internal 35V Switch

Data Sheet

December 20, 2011

© 2011 Zentrum Mikroelektronik Dresden AG

— Rev. 1.00

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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



S

FB

DC

FB

OUT

R

R

V

V

R

V

I





















4

3

EN

LX

AGND

ZLED7015

LED

String

FB

PGND

OVP

VP

VDD

Microcontroller PMW Signal

5V

0V

The output current controlled by the DC voltage on FB can be calculated using equation (2):

(2)

Where

2.2.3

Dimming via PWM Control

An external pulse-width modulated (PWM) signal input can be used to control the LED output current by

driving the output current to a value below the nominal average value defined in section 2.2.1. A

microcontroller can be used to generate the PWM signal. See Figure 2.3 for an example circuit. The PWM

produces a DC voltage with a ripple. This method of controlling dimming is similar to the external DC voltage

control described in section 2.2.2. The duty cycle of the PWM signal regulates the filtered DC voltage level,

which inversely controls the LED output current level. When the duty cycle is at 100%, the output current is at

the minimum. With a 0% duty cycle, the output current is at the maximum.

minimize the filtered PWM voltage ripple.

dimming applications.

Figure 2.3

Example Circuit for Controlling Output Current via a PWM Control Signal