PRODUCT DATASHEET
AAT3123/23A/24
ChargePump
TM
High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications
Features
• V
IN
Range: 2.7V to 5.5V
• Dual Mode 1X and 1.5X Charge Pump for Maximum
Efficiency
• Drives Low-V
F
and High-V
F
Type LEDs
• Up to Six 20mA Outputs (AAT3124)
• Up to Four 20mA Outputs (AAT3123/23A)
• 32-Position Logarithmic Scale with Digital Control
• Simple Serial Control (S
2
Cwire) Interface
• Low Noise Constant Frequency Operation
• 1MHz Switching Frequency
• Small Application Circuit
• Regulated Output Current
• Automatic Soft Start
• No Inductors
• I
Q
<1μA in Shutdown
• Temperature Range: -40°C to +85°C
• 12-Pin TSOPJW Package (AAT3123/23A)
• 16-Pin 4x4mm QFN and 14-Pin TSOPJW Packages
(AAT3124)
General Description
The AAT3123/23A/24 is a low noise, constant frequency
charge pump DC/DC converter that uses a dual mode
load switch (1X) and fractional (1.5X) conversion to
maximize efficiency for white LED applications. The
device can be used to produce current levels up to 20mA
to drive up to six LEDs from a 2.7V to 5.5V input.
Outputs may be operated individually or paralleled for
driving higher-current LEDs. A low external parts count
(two 1μF flying capacitors and two small 1μF capacitors
at V
IN
and OUT) make the AAT3123/23A/24 ideally suited
for small battery-powered applications.
AnalogicTech’s Simple Serial Control™ (S
2
Cwire™) inter-
face is used to enable, disable, and set the LED drive
current with a 32-level logarithmic scale LED brightness
control. The AAT3123/23A/24 has a thermal manage-
ment system to protect the device in the event of a
short-circuit condition at the output pin. Built-in soft-
start circuitry prevents excessive inrush current during
start-up. A high charge pump switching frequency
enables the use of very small external capacitors. A low-
current shutdown feature disconnects the load from V
IN
and reduces quiescent current to less than 1μA. The
device also integrates a test current/auto-disable feature
for each channel. The AAT3123/23A is available in a very
small, Pb-free 12-pin TSOPJW package. The six output
AAT3124 is available in the Pb-free 16-pin 4x4mm QFN
and 14-pin TSOPJW packages.
Applications
•
•
•
•
Color (RGB) Lighting
Programmable Current Source
White LED Backlighting
White Photo Flash for DSCs
Typical Application
VIN
C1+
C1
1μF
V
BATTERY
C
IN
1μF
C
OUT
1μF
VOUT
C1-
C2+
C2
1μF
AAT3124
C2-
D1
D2
D3
D4
D5
D6
EN/SET
EN/SET
GND
D6
D5
D4
D3
D2
D1
3123.2008.03.1.5
www.analogictech.com
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
