AAT3151
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
General Description
The AAT3151 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 AAT3151 is capable of driving
four-channel LEDs at a total of 120mA from a 2.7V
to 5.5V input. The current sinks may be operated
individually or in parallel for driving higher-current
LEDs. A low external parts count (two 1µF flying
capacitors and two small 1µF capacitors at V
IN
and
V
OUT
) makes the AAT3151 ideally suited for small
battery-powered applications.
AnalogicTech's AS
2
Cwire™ (Advanced Simple
Serial Control™) serial digital input is used to
enable, disable, and set current for each LED with
a 16-level logarithmic scale plus four low-current
settings down to 50µA for optimized efficiency, with
a low housekeeping current of only 40µA.
Each output of the AAT3151 is equipped with built-
in protection for V
OUT
short-circuit and auto-disable
for LED failure condition. Built-in soft-start circuitry
prevents excessive inrush current during start-up.
A low-current shutdown feature disconnects the
load from V
IN
and reduces quiescent current to less
than 1µA.
The AAT3151 is available in a space-saving, ther-
mally-enhanced, 12-pin 3x3mm DFN package.
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 50µA
• Low I
Q
(40µA) for Low Current Mode
Tri-Mode 1X, 1.5X, and 2X Charge Pump for
Maximum Efficiency and V
F
Coverage
Drives Four Channels of LEDs
Individual Main/Sub-Group Control
No Inductors, Low Noise Operation
1MHz Constant Switching Frequency
Small Application Circuit
Built-In Thermal Protection
Built-In Auto-Disable for Short-Circuit
Automatic Soft-Start
I
Q
<1µA in Shutdown
Thermally Enhanced 3x3mm 12-Pin DFN
Package
Preliminary Information
Applications
•
•
•
•
Color (RGB) Lighting
Programmable Current Sinks
White LED Backlighting
White Photo-Flash for DSCs
Typical Application
2.7V to 5.5V
C
IN
1µF
V
IN
C1+
C1
1µF
C1-
C2+
AAT3151
C2-
V
OUT
C2
1µF
D1
D2
D3
D4
C
OUT
1µF
EN/SET
EN/SET
D1
D2
D3
GND
D4
3151.2004.10.0.6
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
