AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
Preliminary Information
3152.2004.12.0.9 1
ChargePump
™
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. 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 (80µA 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 condition. Built-in soft-start cir-
cuitry 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 space-saving, ther-
mal-enhanced 12-pin 3x3mm DFN package.
Features
•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
(80µA) 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
• Thermal-Enhanced 3x3mm12-Pin DFN
Package
Applications
• Color (RGB) Lighting
• Programmable Current Sinks
• White LED Backlighting
• White Photo Flash for DSCs
Typical Application
C1
1µF
C2
1µF
D1 D2 D3 D4
C
OUT
1µF
C
IN
1µF
2.7V to 5.5V
EN/SET
V
IN
EN/SET
C1+
C1-
C2+
C2-
V
OUT
D1
D2
D3
D4
GND
AAT3152