PRODUCT DATASHEET
AAT3159
ChargePump
TM
High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Features
• Input Supply Voltage Range: 2.7V to 5.5V
• Tri-Mode (1X/1.5X/2X) Charge Pump
• Maximizes Efficiency
• 1MHz Constant Switching Frequency
• No Inductors, Low Noise Operation
• Drives Four Channels of LEDs up to 40mA/ Channel
• User-Programmable LED Current
• Excellent
LED
Channel-to-Channel
Current
Matching
• Digitally Programmable LED Current with Single-Wire
S
2
Cwire Interface
• 16 Current Levels From 40mA to 50μA
• Low I
Q
(50μA) for Low Current Mode Operation
• True Load Disconnect in Shutdown; I
Q
< 1μA
• Built-In Thermal Protection
• Built-In Auto-Disable for Open LED Circuit
• Automatic Soft-Start Minimizes Inrush Startup
Current
• 2.85x3x1mm TSOPJW-14 Package
General Description
The AAT3159 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
device is capable of driving up to four channels of LEDs
at up to 40mA per channel from a 2.7V to 5.5V input
supply voltage. 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 [C1
and C2] and two small 1μF capacitors [C
IN
and C
OUT
])
makes this part ideally suited for small battery-powered
applications.
AnalogicTech’s patented single-wire Simple Serial
Control™ (S
2
Cwire™) serial digital interface is used to
enable, disable, and set the current for each LED with 16
levels from a maximum of 40mA down to 50μA. The
maximum current level is programmed via an external
resistor. To save power, low-current mode supply current
will be as low as 50μA.
Each output of the AAT3159 is equipped with built- in
protection for V
OUT
short-circuit operation and auto-dis-
able functionality for LED open-circuit conditions. Built-in
soft-start circuitry prevents excessive inrush current
during start-up. A low-current shutdown feature discon-
nects the load from IN and reduces quiescent current to
less than 1μA.
The AAT3159 is available in a Pb-free, space-saving
2.85x3x1mm TSOPJW-14 package.
Applications
•
•
•
•
Cellphones, DSC, Handheld Devices
LED Photo Flash
Programmable Current Sinks
White LED Backlighting
Typical Application
C1
1μF
V
BATTERY
3.6V
C
IN
1μF
C1+
C2+
C2
1μF
C1-
IN
C2-
OUT
WLEDs
OSRAM LW M67C
or equivalent
AAT3159
GND
D1
D1
D2
D3
D4
C
OUT
1μF
EN/SET
2
S Cwire Serial Control
EN/SET
SET
D2
D3
D4
R
SET
26.1kΩ
3159.2007.10.1.0
www.analogictech.com
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
