High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
General Description
The AAT3141 is a low noise, constant frequency
charge pump DC/DC converter that uses a tri
mode load switch (1X), fractional (1.5X), and dou-
bling (2X) conversion to maximize efficiency for
White LED applications. The device produces cur-
rent levels up to 30mA on each of its 4 current
source outputs to drive various arrangements of
LEDs from a 2.7V to 5.5V input. Outputs may be
operated individually or in parallel for driving high-
er-current LEDs. A low external parts count (two
1µF flying capacitors and two small 1µF capacitors
at V
IN
, and CP) make the AAT3141 ideally suited
for small battery-powered applications.
Analogic Tech™'s Advanced Simple Serial Control™
(AS
2
Cwire™) digital input is used to enable, disable
and set the LED drive current with a 32 level loga-
rithmic scale LED brightness control. The AAT3141
has a thermal management system to protect the
device in the event of a short circuit condition at an
output pin. Built-in soft-start circuitry prevents exces-
sive inrush current during start-up. A high charge
pump switching frequency enables the use of very
small external capacitors. In shutdown mode, the
device disconnects the load from V
IN
and reduces
quiescent current to less than 1µA. The AAT3141 is
available in the very small 12 pin TSOPJW package.
AAT3141
Features
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ChargePump
™
Tri Mode 1x, 1.5x, and 2x Charge Pump for
Maximum Efficiency and V
F
coverage
Drives Low-V
F
& High-V
F
Type LEDs
Up to 4, 30mA Outputs
AS
2
Cwire Independent 3+1 output addressing
32 Position Logarithmic Scale with Digital
Control
Low Noise Constant Frequency Operation
1MHz Switching Frequency
Small Application Circuit
Regulated Output Current
Automatic Soft-Start
V
IN
Range: 2.7V to 5.5V
No Inductors
Iq < 1µA in Shutdown
12 pin TSOPJW package
Preliminary Information
Applications
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White LED Backlighting
White Photo-Flash for DSCs
Color (RGB) Lighting
Programmable Current Sources
Typical Application
V
IN
C1+
C1
1µF
CP
V
BATTERY
C
IN
1µF
C
CP
1µF
C1-
C2+
C2
1µF
AAT3141
C2-
D1
D2
D3
D4
EN/SET
EN/SET
D4
GND
D3
D2
D1
3141.2004.07.0.91
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
