AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
General Description
The AAT2846 is a highly integrated charge pump
with dual linear regulators optimized for systems
powered from lithium-ion/polymer batteries. The
charge pump provides power for both white LED
backlight and flash. Six backlight LEDs can be driv-
en at up to 30mA each, while up to two flash LEDs
can be driven at up to 600mA total. AnalogicTech's
AS
2
Cwire™ (Advanced Simple Serial Control™) sin-
gle-wire interface is used to enable, disable, and set
the current to one of 32 levels for the backlight and
one of 16 levels for the flash. An external resistor sets
the maximum flash current. Backlight current match-
ing is 1% for uniform display brightness, and flash
current matching is 4% for uniform power dissipation.
The AAT2846 offers two high-performance low-
noise MicroPower™ low dropout (LDO) linear regu-
lators. Both regulators use individual enable inputs
and each will supply up to 200mA load current. LDO
ground pin current is only 80µA, making the
AAT2846 ideal for battery-operated applications.
The AAT2846 is equipped with built-in short-circuit
and over-temperature protection. The soft start cir-
cuitry prevents excessive inrush current at start-up
and mode transitions.
The AAT2846 is available in a Pb-free TQFN44-28
package and operates over the -40°C to +85°C
ambient temperature range.
Features
•
•
ChargePump
™
•
•
•
•
•
Input Voltage Range: 2.7V to 5.5V
Tri-Mode Charge Pump:
— Drives up to Six Backlight LEDs and Two
Flash LEDs
— 32 Programmable Backlight Current
Settings Ranging from 95µA to 30mA
— 16 Programmable Flash Current Settings
— Maximum Flash LED Current
Programmable using External Resistor
— 2MHz Switching Frequency
Two Linear Regulators:
— 200mA Output Current
— 200mV Dropout Voltage
— Output Voltage Adjustable from 1.2V to
V
BATTERY
— Output Auto-Discharge for Fast Shutdown
— Individual LDO Enable Inputs
Built-In Thermal Protection
Automatic Soft Start
-40°C to +85°C Temperature Range
TQFN44-28 Package
Applications
•
•
•
Camera-Enabled Mobile Devices
Digital Still Cameras
Multimedia Mobile Phones
Typical Application
C
1
1μF
C
2
1μF
C1+
C1- C2+
C2-
V
OUT
IN
V
BAT
OUT
C
IN
4.7μF
ENABLE/SET
EN_FLASH
IN
AAT2846
BL1
BL2
BL3
BL4
BL5
BL6
FL1
FL2
OUTA
C
OUT
2.2μF
ENS
FEN
CT
FSET
C
T
0.1μF
R
FSET
280k
C
BYP
0.1μF
REF
V
OUT
LDOA
R
2A
C
OUTA
FBA
R
1A
ENA
ENB
AGND
OUTB
R
2B
FBB
PGND
R
1B
EN_LDOA
EN_LDOB
V
OUT
LDOB
C
OUTB
2846.2007.08.1.0
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
