AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
Preliminary Information
3141.2004.07.0.91 1
ChargePump
™
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.
Features
• 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
Applications
• White LED Backlighting
• White Photo-Flash for DSCs
• Color (RGB) Lighting
• Programmable Current Sources
Typical Application
C
IN
1µF
V
BATTERY
C
CP
1µF
EN/SET
C1
1µF
C2
1µF
D3 D2 D1
VIN
CP
C1+
C1-
C2+
C2-
D1
D2
D3
D4
EN/SET
GND
AAT3141
D4