Multi-Mode Charge Pump for
White LED Backlight and Flash Applications
General Description
The AAT2801 is a member of AnalogicTech's Total
Power Management IC™ (TPMIC™) product family.
It has a dual charge pump architecture designed to
support both the white LED backlight and flash appli-
cations for systems operating with Lithium-Ion bat-
teries. The backlight charge pump provides power
required to drive up to four LEDs. To maximize
power efficiency, it automatically selects 1X, 1.5X, or
2X mode. The device produces current levels up to
30mA on each of its four current source outputs.
AnalogicTech's Simple Serial Control™ (S
2
Cwire™)
interface is used to enable, disable, and set the LED
drive current with a 32-level logarithmic scale LED
brightness control.
The flash charge pump is a charge pump doubler
with a regulated output voltage. It is designed to
deliver 120mA of continuous current and up to
250mA of pulsed current. It has an independent
enable pin for improved power savings.
The AAT2801 is equipped with AnalogicTech’s
AutoBias™ technology which allows individual LEDs
to be powered either by charge pump or battery
input, determined internally and automatically to
maximize the power efficiency even with a large dif-
ference in LED forward voltage.
The AAT2801 has thermal protection and built-in
soft-start circuitry. A high charge pump switching fre-
quency enables the use of very small external capac-
itors. The AAT2801 is available in the 16-pin
TDFN44 package.
AAT2801
Features
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ChargePump
™
V
IN
Range: 2.7V to 5.5V
Dual Charge Pump
— Flash: Charge Pump Doubler
— Backlight: Tri-Mode Charge Pump
Drives Low-V
F
and High-V
F
LEDs
Up to Four 30mA Outputs
32-Position Logarithmic Scale with Digital
Control
Low Noise Constant Frequency Operation
1MHz Switching Frequency
AutoBias Technology
Regulated 4.5/5.0 Volts V
OUT_FLASH
Up to 250mA of Current for Flash
Automatic Soft Start
No Inductors
I
Q
<1µA in Shutdown
Available in 16-pin TDFN44 Package
Applications
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Display Modules
Mobile Phones
PDAs
Smart Phones
Typical Application
C1
1μF
C2
1μF
C3
1μF
C1
+
IN
C1
-
C2
+
C2
-
C3
+
C3
-
C
F
1μF
CP
V
IN
C
IN
1μF
C
CP
1μF
R
B
OUT_FLSH
Flash LED
AAT2801
D1
D2
D3
D4
D4
D3
D2
Backlight
D1
EN/SET
Flash Enable
EN/SET
EN_FLSH
GND
2801.2006.04.1.3
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
