AAT3159 Datasheet, PDF (1/15 Pages) Advanced Analogic Technologies – High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications

ChargePump^TM
PRODUCT DATASHEET
AAT3159
High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
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™ (S²Cwire™) 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.
Typical Application
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
S²Cwire 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
Applications
• Cellphones, DSC, Handheld Devices
• LED Photo Flash
• Programmable Current Sinks
• White LED Backlighting
C1
1μF
VBATTERY
3.6V
CIN
1μF
EN/SET
S²Cwire Serial Control
RSET
26.1kΩ
C1+
C2+
C1-
C2-
IN
OUT
AAT 3159
GND
D1
EN/SET
D2
SET
D3
D4
C2
1μF
WLEDs
OSRAM LW M67C
or equivalent
D1
D2
D3
D4
COUT
1μF
3159.2007.10.1.0
www.analogictech.com
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