AL3158
HIGH EFFICIENCY 1x/2x CHARGE PUMP
FOR WHITE LED APPLICATIONS
Description
Pin Assignments
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 VIN and VOUT) 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 VIN 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.
Applications
Features
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Mobile Phone White LED Backlighting and Indicators
PDA White LED Backlighting
Battery-operated Phone Main and Sub Screen White LED
Backlighting
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VIN 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
VOUT short circuit and Thermal Protections
Soft Start for reducing inrush current
Under Voltage Lockout Protection
IQ <1µA in Shutdown
Thermally-Enhanced QFN3030-20 Package: Available in “Green”
Molding Compound (No Br, Sb)
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Lead Free Finish/ RoHS Compliant (Note 1)
Notes: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at
http://www.diodes.com/products/lead_free.html
Typical Application Circuit
8
9
VIN
VIN
CP
1uF
C1
2.2uF
CIN
EN3
EN1
EN2
7
CN
AL3158
11
VOUT
2.2uF
COUT
D5
LED
D6
LED
D7
LED
D8
LED
D9
LED
D3
LED
D4
LED
D1
LED
D2
LED
3
12
13
14
EN1
D1
D2
D3
D4
D5
D6
EN1
5
4
EN2
EN3
EN2
EN3
15
16
18
20
1
D7
D8
D9
2
PGND
GND
6
17
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www.diodes.com
January 2011
© Diodes Incorporated
AL3158
Document number: DS35047 Rev. 2 - 2