AL3158

HIGH EFFICIENCY 1x/2x CHARGE PUMP

FOR WHITE LED APPLICATIONS

AL3158

Document number: DS35047 Rev. 1 - 2

1 of 10

www.diodes.com

September 2010

© Diodes Incorporated

Description

The AL3158 is a low noise, constant frequency charge pump

DC/DC converter that uses a Dual mode load switch (1x), and (2x)

conversion for white LED applications. The AL3158 is capable of

driving three groups of three LED channels at 20mA from a 2.7V to

5.5V input. The current sinks may be operated using three simple

PWM dimming inputs individually or in parallel for driving higher-

current LEDs. Low external part counts (one 1µF flying capacitor

suited for small, battery-powered applications.

AL3158 PWM dimming inputs are used to enable, disable device

and dimming LED current with a fixed default current settings at

20mA or other factory programming options available.

Each output of the AL3158 is equipped with built-in protection for

soft-start circuitry prevents excessive inrush current during start-up

and mode switching. A low-current shutdown feature disconnects

The AL3158 is available in a lead-free, space-saving, thermally

enhanced 20-pin 3 x 3mm QFN package.

Features

• V

• Up to 93% Max Power Efficiency

• 1% Current Matching Accuracy Between Channels

• Three simple PWM dimming for RGB or WLED

• Low transition threshold voltage typical 150 mV

• Dual-Mode 1x and 2x Charge Pump

• Drives up to 3 + 3 + 3 Channels of LEDs

• 1.2 MHz Constant Switching Frequency

• V

• Soft Start for reducing inrush current

• Under Voltage Lockout Protection

• I

• Thermally-Enhanced QFN3030-20 Package: Available in “Green”

Molding Compound (No Br, Sb)

• Lead Free Finish/ RoHS Compliant (Note 1)

Pin Assignments

Applications

• Mobile Phone White LED Backlighting and Indicators

• PDA White LED Backlighting

• Battery-operated Phone Main and Sub Screen White LED

Backlighting

Notes:

http://www.diodes.com/products/lead_free.html

Typical Application Circuit

2.2uF

AL3158

D4

D1

D2

D3

PGND

3

8

1uF

7

9

6

11

15

D1

LED

14

D2

LED

13

D3

LED

12

D4

LED

2.2uF

5

D5

D6

D7

D8

D9

D5

LED

D6

LED

D7

LED

D8

LED

D9

LED

16

18

20

1

2

4

GND

17

EN1

EN2

EN3

EN1

EN2

EN3

EN1

EN2

EN3