AL3159

HIGH EFFICIENCY 1x/2x CHARGE PUMP

FOR WHITE LED APPLICATIONS

AL3159

Document number: DS35048 Rev. 2 - 2

6 of 10

www.diodes.com

January 2011

© Diodes Incorporated

Functional Description

The AL3159 is a dual-mode high efficiency charge pump

(1x and 2x) device, driving nine LED channels with three

simple

logic

control

inputs,

intended

for

white

LED backlight applications. An internal comparator circuit

compares the voltage at each constant current sink input

against a reference voltage. To ensure maximum power

efficiency, the most appropriate switching mode (1x and

2x) is automatically selected.

The AL3159 requires only three external components: one

one 2.2µF ceramic input

The each output channel of the AL3159 can drive nine

individual

LEDs

with

a

maximum

current

of

fixed

manufacture setting (20mA or 30mA) per channel. These

can be paralleled to give a total maximum output current of

270mA.

Disabled Current Sinks

Unused current channels must be disabled by connecting

the sinks to VOUT with only a small sense current flowing

through the disabled channel.

Soft-Start

Soft-start is incorporated to prevent excessive inrush

current

during

power-up,

mode

switching,

and

transitioning out of stand-by mode.

Short-Circuit Protection

Short-circuit protection function is incorporated to prevent

excessive load current when either flying cap terminals or

output pin electrically tied to a very lower voltage or

ground.

Over-Voltage Protection

Over-Voltage Protection function is incorporated to limit

the output voltage under a safe value to avoid on-chip

device breakdown.

Under-Voltage Lockout

Under-Voltage lockout feature disables the device when

the input voltage drops below UVLO threshold.

Thermal Auto Shutdown

When the die temperature exceeds the thermal limit, the

device will be disabled and enter stand-by mode. The

operation resumes whenever the die cools off sufficiently.

CTL<3:1>

LED ON/OFF CONTROL

000

ALL OFF

001

LED1~LED2 ON

010

LED3~LED5 ON

011

LED6~LED9 ON

100

LED9 ON

101

LED6~LED8 ON

110

LED1~LED5 ON

111

ALL ON