AAT3134
High Efficiency 1X/1.5X Fractional
Charge Pump for White LED Applications
General Description
The AAT3134 is a low noise, constant frequency
charge pump DC/DC converter that uses a dual
mode load switch (1X) and fractional (1.5X) con-
version to maximize efficiency for white LED appli-
cations. The device can be used to produce current
levels up to 20mA in each of its six outputs to drive
LEDs from a 2.7V to 5.5V input. Outputs may be
operated individually or paralleled for driving high-
er-current LEDs. A low external parts count (two
1µF flying capacitors and two small 1µF capacitors
at V
IN
and OUT) make the AAT3134 ideally suited
for small battery-powered applications.
AnalogicTech's Simple Serial Control™ (S
2
Cwire™)
interface is used to enable, disable, and set the
LED drive current in two groups of four outputs and
two outputs with multiple-level, independently-con-
trolled brightness scales. The AAT3134 has a ther-
mal management system to protect the device in
the event of a short-circuit condition at the 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. A low-current shutdown feature
disconnects the load from V
IN
and reduces quies-
cent current to less than 1µA. The AAT3134 is
available in a Pb-free 16-pin QFN44 package and is
rated over the -40°C to +85°C temperature range.
Features
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ChargePump
™
V
IN
Range: 2.7V to 5.5V
<1.0µA of Shutdown
1MHz Switching Frequency
Fully Independent Display Lighting
Dual Mode 1X and 1.5X Charge Pump for
Maximum Efficiency
Drives Low-V
F
and High-V
F
Type LEDs
Up to Six 20mA Outputs
Multi-Position Brightness Scale with Digital
Control
Low Noise Constant Frequency Operation
Small Application Circuit
Regulated Output Current
Automatic Soft Start
No Inductors
16-Pin QFN44 Package
-40°C to +85°C Temperature Range
Applications
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Color (RGB) Lighting
Programmable Current Source
White LED Backlighting
White LED Photo Flash for Digital Still Cameras
Typical Application
VIN
C1+
C1
1µF
VOUT
V
BATTERY
C
IN
1µF
C
OUT
1µF
C1-
C2+
C2
1µF
AAT3134
C2-
D1
D2
D3
D4
D5
D6
EN/SET
EN/SET
GND
D4
D3
D2
D1
D6
D5
Sub
Display
Main
Display
3134.2005.12.1.1
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ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
