Diodes AL3158 User Manual
Al3158, New prod uc t description, Features
AL3158
HIGH EFFICIENCY 1x/2x CHARGE PUMP
FOR WHITE LED APPLICATIONS
AL3158
Document number: DS35047 Rev. 2 - 2
1 of 10
January 2011
© Diodes Incorporated
NEW PROD
UC
T
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
and two 2.2µF capacitors at V
IN
and V
OUT
) make this part ideally
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
V
OUT
short circuit and auto-disable for LED short conditions. Built-in
soft-start circuitry prevents excessive inrush current during start-up
and mode switching. A low-current shutdown feature disconnects
the load from V
IN
to reduce quiescent current less than 1µA.
The AL3158 is available in a lead-free, space-saving, thermally
enhanced 20-pin 3 x 3mm QFN package.
Features
• V
IN
Range: 2.7V to 5.5V
• 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
OUT
short circuit and Thermal Protections
• Soft Start for reducing inrush current
• Under Voltage Lockout Protection
• I
Q
<1µA in Shutdown
• 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: 1.
EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at
Typical Application Circuit
V
IN
2.2uF
C
IN
AL3158
C
P
C
N
V
OUT
D4
D1
D2
D3
PGND
3
8
V
IN
1uF
C
1
7
9
6
11
15
D1
LED
14
D2
LED
13
D3
LED
12
D4
LED
2.2uF
C
OUT
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