AAT3140
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
™
ChargePump
General Description
Features
The AAT3140 is a low noise, constant frequency
charge pump DC/DC converter that uses a tri-mode
load switch (1X), fractional (1.5X), and doubling (2X)
conversion to maximize efficiency for white LED appli-
cations. The device produces current levels up to
30mA on each of its four 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 higher-current LEDs. Alow external
parts count (two 1µF flying capacitors and two small
1µF capacitors at VIN and CP) make the AAT3140 ide-
ally suited for small battery-powered applications.
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VIN Range: 2.7V to 5.5V
Tri-Mode 1X, 1.5X, and 2X Charge Pump for
Maximum Efficiency and VF Coverage
Drives Low-VF and High-VF Type LEDs
Up to Four 30mA Outputs
32-Position Logarithmic Scale with Digital
Control
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Low Noise Constant Frequency Operation
1MHz Switching Frequency
AutoBias Technology
Small Application Circuit
Regulated Output Current
Automatic Soft Start
The AAT3140 is equipped with AnalogicTech’s unique
AutoBias™ technology which allows individual LEDs
to be powered either by charge pump or battery input,
determined internally and automatically to maximize
the power efficiency even with a large difference in
LED forward voltage.
No Inductors
IQ < 1µA in Shutdown
12-Pin TSOPJW Package
2
AnalogicTech's Simple Serial Control™ (S Cwire™)
Applications
digital input is used to enable, disable, and set the
LED drive current with a 32-level logarithmic scale
LED brightness control. The AAT3140 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 excessive 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
VIN and reduces quiescent current to less than 1µA.
The AAT3140 is available in the very small, Pb-free
12-pin TSOPJW package.
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Color (RGB) Lighting
Programmable Current Sources
White LED Backlighting
White Photo Flash for Digital Still Cameras
Typical Application
VIN
CP
C1+
C1
1μF
C1-
C2+
CIN
CCP
C2
VBATTERY
AAT3140
1μF
1μF
1μF
C2-
D1
D2
D3
D4
EN/SET
EN/SET
GND
D4
D3
D2
D1
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