MP3304 –36V, 1.3A, STEP-UP WHITE LED DRIVER WITH HIGH FREQUENCY TRUE PWM DIMMING

MP3304 Rev. 0.91

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10

4/19/2010

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MP3304A

SW

IN

ISET

LED

PGND

GND

EN

LED+

LED-

C2

330nF

50V

D2

5.6V

7.5

ZENER

D1

B0540

L1

10uH

Optional

Bias Circuit

GND

EN

VIN

3.3V -18V

C1

10uF

25V

C3

0.1uF

50V

2

31

6

7

5

8

Figure 6 — Driving 27 WLEDs (9 WLEDs in Series and 3 Strings Paralleled) with 3.3V-18V Input Voltage

In order to improve the MOSFET on-resistance at low input voltage and make the chip compatible for

high input voltage, the additional bias circuit should be used.

MP3304A

SW

LED

IN

ISET

PGND

GND

EN

GND

EN

LED+

LED-

VIN

4.5V-18V

C1

10uF

25V

C4

330nF

50V

C3

0.1uF

25V

Q2

2N3904

D2

5.6V

ZENER

Required Bias Circuit

for High Input Voltage

L1

D1

10uH

B0540

7

8

2

31

6

5

Figure 7 — Wide Input Voltage Step-up Converter for 27 WLEDs

( 9 WLEDs in Series and 3 Strings Paralleled )