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
LED's from a 2.7V to 5.5V input. Outputs may be
operated individually or paralleled for driving high-
er-current LED's. Low external parts counts (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 16-pin quad QFN package.
Features
•V
IN
Range: 2.7 - 5.5 Volts
• < 1.0µA of Shutdown
• 1 MHz Switching Frequency
• Fully Independent Display Lighting
• Dual Mode 1x and 1.5x Charge Pump for
Maximum Efficiency
• Drives Low-V
F
& High-V
F
Type LED's
• 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 QFN package
• -40 to +85°C Temperature range
Applications
• White LED Backlighting
• White Photo-Flash for DSC's
• Color (RGB) Lighting
• Programmable Current Source
AAT3134
High Efficiency 1X/1.5X Fractional
Charge Pump for White LED Applications
Typical Application
C
IN
1µF
V
BATTERY
C
OUT
1µF
EN/SET
C1
1µF
C2
1µF
D3 D2 D1
D6
V
IN
V
OUT
C1+
C1-
C2+
C2-
D1
D2
D3
D5
EN/SET
GND
AAT3134
D4
D5
D6
D4
Main
Display
Sub
Display
3134.2004.04.1.0 1
ChargePump
™