AAT3158
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
General Description
The AAT3158 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 AAT3158 is capable of
driving up to four LED channels at 20mA per chan-
nel from a 2.7V to 5.5V input. The current sinks
may be operated individually or in parallel for driv-
ing higher current LEDs. A low external parts count
(two 1µF flying capacitors and two small 1µF
capacitors at V
IN
and V
OUT
) make this part ideally
suited for small, battery-powered applications.
AnalogicTech's
S
2
Cwire™
(Simple
Serial
Control™) serial digital input is used to enable, dis-
able, and set current for each LED with 16 settings
down to 50µA. The low current mode supply cur-
rent can be as low as 50µA to save power.
Each output of the AAT3158 is equipped with built-
in protection for V
OUT
short circuit and auto disable
for load short-circuit conditions. Built-in soft-start
circuitry prevents excessive inrush current during
start-up. A low current shutdown feature discon-
nects the load from V
IN
and reduces quiescent cur-
rent to less than 1µA.
The AAT3158 is available in a Pb-free, space-saving
2.85x3.0mm TSOPJW-12 package.
Features
•
•
•
•
•
•
•
•
•
•
•
•
ChargePump
™
V
IN
Range: 2.7V to 5.5V
Fully Programmable Current with Single Wire
— 16 Current Levels
— Four Low Current Settings Down to 50µA
Low I
Q
(50µA) for Low Current Mode
Tri-Mode 1X, 1.5X, and 2X Charge Pump for
Maximum Efficiency and V
F
Coverage
Drives Up to Four LED Channels
No Inductors, Low Noise Operation
1MHz Constant Switching Frequency
Small Application Circuit
Built-In Thermal Protection
Automatic Soft-Start
I
Q
<1µA in Shutdown
2.85x3mm TSOPJW-12 Package
Applications
•
•
•
•
Color (RGB) Lighting
Programmable Current Sinks
White LED Backlighting
White Photo Flash for Digital Still Cameras
Typical Application
C1+
C2+
C2-
VOUT
C
OUT
1µF
C
1
1µF
2.7V to 5.5V
C
IN
1µF
C
2
1µF
C1-
VIN
AAT3158
GND
D1
D2
D3
D4
D1
D2
D3
D4
EN/SET
EN/SET
3158.2006.02.1.0
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
