High Efficiency 1X/1.5X/2X Charge
Pump for White LED Applications
General Description
The AAT3169 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 applications. The AAT3169 is capable of driv-
ing six LEDs for a total of 180mA from a 2.7V to
5.5V input. The current sinks may be operated indi-
vidually or in parallel for driving higher current LEDs.
A low external parts count (two 1µF flying capacitors
and two small 1µF capacitors at IN and OUTCP)
make this part ideally suited for small, battery-pow-
ered applications.
AnalogicTech's AS
2
Cwire™ (Advanced Simple Serial
Control™) serial digital input is used to enable, dis-
able, and set current for each LED with a 16-level
logarithmic scale plus four low-current settings down
to 115µA. For optimized efficiency, low-current set-
tings require only 65µA of housekeeping current.
Each output of the AAT3169 is equipped with built-
in protection for output short-circuit and auto-dis-
able for load short-circuit conditions. Built-in soft-
start circuitry prevents excessive inrush current
during start-up. A low-current shutdown feature dis-
connects the load from the input and reduces qui-
escent current to less than 1µA.
The AAT3169 is available in a Pb-free, space-sav-
ing, thermally-enhanced 16-pin 4x4mm QFN pack-
age or a low-profile 14-pin 3x3mm STDFN pack-
age and is rated over the -40°C to +85°C tempera-
ture range.
AAT3169
Features
•
•
ChargePump
™
•
•
•
•
•
•
•
•
•
•
•
V
IN
Range: 2.7V to 5.5V
Fully Programmable Current with Single Wire
— 16-Step Logarithmic Scale
— 15/20/30mA Max Current
— Four Low-Current Settings Down to 115µA
— Low I
Q
(65µA) for Single-Channel, Low-
Current Mode
Tri-Mode 1X, 1.5X, and 2X Charge Pump for
Maximum Efficiency and V
F
Coverage
Drives Up to Six LEDs
Individual Main-Sub (5-1) Group Control
No Inductors, Low Noise Operation
1MHz Constant Switching Frequency
Small Application Circuit
Built-In Thermal Protection
Built-In Auto-Disable for Open Circuit
Automatic Soft Start
I
Q
<1µA in Shutdown
Thermally-Enhanced STDFN33-14 or
QFN44-16 Package
Applications
•
•
•
•
•
Color (RGB) Lighting
Programmable Current Sink
Transmissive Displays
White LED Backlighting
White Photo Flash for Digital Still Cameras
Typical Application
C1+
C1
1µF
C2+
C2
1µF
Main
Sub
C1-
C2-
OUTCP
C
OUT
1µF
D1
D2
2.7V to 5.5V
C
IN
1µF
IN
AAT3169
D1
D2
D3
D3
D4
D5
D6
EN/SET
EN/SET
D4
D5
D6
3169.2006.08.1.2
1
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
