AAT3142
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
™
ChargePump
General Description
Features
The AAT3142 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 three 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 VIN and CP) make the AAT3142 ideally 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 Three 30mA Outputs
32-Position Logarithmic Scale with Digital
Control
Low Noise Constant Frequency Operation
1MHz Switching Frequency
Small Application Circuit
Regulated Output Current
Automatic Soft Start
No Inductors
IQ < 1µA in Shutdown
12-Pin TSOPJW Package
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AnalogicTech's Simple Serial Control™ (S2Cwire™)
digital input is used to enable, disable, and set the
LED drive current with a 32-level logarithmic scale
LED brightness control. The AAT3142 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 switch-
ing frequency enables the use of very small external
capacitors. In shutdown mode, the device discon-
nects the load from VIN and reduces quiescent cur-
rent to less than 1µA. The AAT3142 is available in
the very small, Pb-free 12-pin TSOPJW package.
Applications
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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
AAT3142
1µF
1µF
1µF
C2-
D1
D2
D3
EN/SET
EN/SET
GND
D3
D2
D1
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