High Efficiency 1.5X Fractional Charge
Pumps For White LED Applications
General Description
The AAT3113 and AAT3114/14A are low noise, con-
stant frequency charge pump DC/DC converters
that use fractional (1.5X) conversion to increase effi-
ciency in white LED applications. The devices can
be used to produce current levels up to 20mA for
each output from a 2.7V to 5.5V input. A low exter-
nal parts count (two 1µF flying capacitors and two
small bypass capacitors at V
IN
and OUT) makes
these devices ideally suited for small, battery-pow-
ered applications.
AnalogicTech’s Simple Serial Control™ (S
2
Cwire™)
interface is used to enable, disable, and set the
LED drive current for 32-level logarithmic scale LED
brightness control. AAT3113 and AAT3114/14A
devices have a thermal management system for
protection in the event of a short-circuit condition on
any of the output pins. Built-in soft-start circuitry
prevents excessive inrush current during start-up.
A high switching frequency enables the use of small
external capacitors. A low-current shutdown feature
disconnects the load from V
IN
and reduces quies-
cent current to less than 1µA. The AAT3113 pro-
vides four LED current source outputs, and the
AAT3114/14A provides six. The AAT3113 is avail-
able in a Pb-free 12-pin TSOPJW package, and the
AAT3114/14A is available in a Pb-free 16-pin QFN
package.
AAT3113, AAT3114/14A
ChargePump
™
Features
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AAT3113: Four Outputs
AAT3114/14A: Six Outputs
20mA Full-Scale Current
Simple Serial Control (S
2
Cwire) Interface
— 32-Position Logarithmic Scale with Digital
Control
Low Noise Constant Frequency Operation
33% Less Input Current Than Doubler
Charge Pump
High Accuracy Brightness Matching
Small Application Circuit
Regulated Output Current
Automatic Soft Start
V
IN
Range: 2.7V to 5.5V
No Inductors
600kHz Switching Frequency
I
Q
<1µA in Shutdown
Temperature Range: -40°C to 85°C
12-Pin TSOPJW Package (AAT3113)
16-Pin QFN Package (AAT3114/14A)
Applications
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Programmable Current Source
White LED Backlighting
Typical Application
VIN
C1+
C1
1μF
OUT
V
BATTERY
C
IN
1μF
C
OUT
1μF
C1-
C2+
C2
1μF
AAT3114/14A
C2-
D1
D2
D3
D4
D5
D6
EN/SET
EN/SET
GND
D6
D5
D4
D3
D2
D1
3113.2006.07.1.9
1
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
