PRODUCT DATASHEET
AAT2846
ChargePump
TM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
Features
• 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
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 driven 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™) single-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
matching 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 regulators. Both
regulators use individual enable inputs and each will
supply up to 200mA load current. LDO ground pin cur-
rent 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 circuitry pre-
vents excessive inrush current at start-up and mode
transitions.
The AAT2846 is available in a Pb-free TQFN44-28 pack-
age and operates over the -40°C to +85°C ambient
temperature range.
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
2846.2008.03.1.1
www.analogictech.com
1
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