AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
General Description
The AAT3152 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 AAT3152 is capable of driving
four-channel LEDs from a 2.7V to 5.5V input. The
current sinks may be operated individually or in par-
allel 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 this part ide-
ally suited for small, battery-powered applications.
AnalogicTech's S
2
Cwire™ (Simple Serial Control™)
serial digital input is used to enable, disable, and
set current for each LED with eight settings (20mA
down to 50µA) including main/sub-display group
control. The AAT3152 consumes extremely low cur-
rent internally (50µA typical) at light load for opti-
mized efficiency.
Each output of the AAT3152 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 AAT3152 is available in a Pb-free, space-sav-
ing, thermally-enhanced 12-pin 3x3mm TDFN
package.
Features
•
•
ChargePump
™
•
•
•
•
•
•
•
•
•
•
V
IN
Range: 2.7V to 5.5V
Fully Programmable Current with Single Wire
— Eight-Step Current: 20mA to 50µA
— Individual Main-Sub Group Control
— Low I
Q
(50µA) at Light Load
Tri-Mode 1X, 1.5X, and 2X Charge Pump for
Maximum Efficiency and V
F
Coverage
Drives 1-4 Channels of LEDs
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 TDFN
Package
Applications
•
•
•
•
Color (RGB) Lighting
Programmable Current Sinks
White LED Backlighting
White Photo Flash for Digital Still Cameras
Typical Application
2.7V to 5.5V
C
IN
1µF
VIN
C1+
C1
1µF
C1-
C2+
AAT3152
C2-
VOUT
C2
1µF
D1
D2
D3
D4
C
OUT
1µF
EN/SET
EN/SET
D1
D2
D3
GND
D4
3152.2005.08.1.2
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
