AAT2801
Multi-Mode Charge Pump for
White LED Backlight and Flash Applications
2801.2006.04.1.3 1
ChargePump
™
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.
Features
•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
• Display Modules
• Mobile Phones
• PDAs
• Smart Phones
Typical Application
AAT2801
C IN
1 µ F
V IN
C
CP
1 µ F
EN/SET
C1
1 µ F
D3 D2 D1
IN
CP
C1
+
C1
-
D2
GND
D4
Backlight
Flash LED
C2
1 µ F
C3
1 µ F
C2
+
C2
-
C3
+
C3
-
OUT_FLSH
C
F
R
B
1 µ F
Flash Enable
EN/SET
EN_FLSH
D1
D3
D4