ZLED7001

Universal LED Driver with Temperature Compensation

Data Sheet

August 12, 2010

© 2010 Zentrum Mikroelektronik Dresden AG — Rev. 1.1

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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Circuit Description

The ZLED7001 is a peak current-mode-control LED driver IC that operates in constant off-time mode,

enabling proper LED current control without additional loop compensation or high-side current sensing. The

ZLED7001 supports both linear and PWM control of the LED current. Only a few external components are

needed for typical applications. It is well-suited for buck LED driver applications.

2.1.

ZLED7001 Block Diagram

Bandgap

Blanking

480ns

RS

POR

UVLO

nLED

L1

R2

NTC

5

6

D1

Q1

C1

R1

8 to 450 VDC

2

3

1

CS

LD

PWMD

GATE

GND

4

7

ZLED7001

Timing

Circuit

7.1V Clamp

R

R

R

0.24V

0.05V

+

+

–

–

+

–

0.24V

Driver

R

S

Q

CMP1

CMP2

CMP3

8

vdda

vdda

vddd

Voltage

Regulator

2.2.

Application Signal Flow

flop in the ZLED7001, turning on the GATE pin driver, which is connected to the Q1 external MOSFET. When

Q1 turns on, a ramp current flows through the LED(s), the L1 external inductor, and the external sense

comparators continually compare to the voltage at its LD pin and its internal 240mV reference. If either

comparator goes high and the blanking time is expired (see Table 1.3), the flip-flop is reset, causing the GATE

pin output to go low, shutting off the current through the LED(s).

The peak current control scheme with constant off-time can easily operate at duty cycles higher than 0.5 and

also gives inherent input voltage rejection, making the LED current almost insensitive to input voltage

variations.