AAT2842 Datasheet, PDF (1/21 Pages) Advanced Analogic Technologies – High-Current Charge Pump with S2Cwire™ Control and Dual LDO for Backlight and Flash

AAT2842
High-Current Charge Pump with S²Cwire™
Control and Dual LDO for Backlight and Flash
General Description
Features
ChargePump^™
The AAT2842 is a highly integrated charge pump
with dual linear regulators optimized for systems
operating with lithium-ion/polymer batteries. The
charge pump provides power for both white LED
backlight/keypad and flash. Up to four backlight
LEDs can be driven at up to 30mA each and key-
pad LEDs can be driven using lower currents set by
the S²Cwire interface. In addition, up to four flash
LEDs can be driven with up to 600mA total. Two
separate S²Cwire™ (Simple Serial Control™) serial
digital interfaces are used to enable, disable, and
set the current to one of 16 levels for both backlight
and flash LEDs. Backlight/keypad and flash current
settings are also controlled through external resis-
tors for increased versatility with reduced accuracy
and matching. Backlight/keypad current matching
is 1% for uniform display brightness, and flash cur-
rent matching is 4% for uniform power dissipation.
An integral flash timer set by an external capacitor
protects the flash LED should a fault occur.
The AAT2842 offers two high-performance
MicroPower™ low dropout (LDO) linear regulators.
A single enable input controls both regulators and
each supplies up to 200mA to the load. Both LDOs
consume only 85µA quiescent current, making
them ideal for battery-operated applications.
The AAT2842 is equipped with built-in short-circuit
and over-temperature protection. The charge pump
soft-start circuitry prevents excessive inrush current
at start-up. The product is available in a Pb-free,
space-saving TQFN44-28 package and operates
over the -40°C to +85°C ambient temperature range.
• V_IN Range: 2.7V to 5.5V
• Tri-Mode Charge Pump:
— Drives up to Four Backlight/Keypad and
Four Flash LEDs
— Separate S²Cwire Control for
Backlight/Keypad and Flash Currents
— Backlight/Keypad and Flash Current Set
by Separate External Resistors
— Flash Timer Set with External Capacitor
— Up to 2MHz Switching Frequency
• Two Linear Regulators:
— 200mA Output Current
— 200mV Dropout
— Output Voltage Adjustable from 1.2V to
V_BATTERY
— Output Auto-Discharge for Fast Shutdown
— 85µA Quiescent Current
• Built-In Thermal Protection
• Automatic Soft Start
• -40°C to +85°C Temperature Range
• Available in 4x4mm TQFN44-28 Package
Applications
• Camera-Enabled Mobile Devices
• Digital Still Cameras
• Multimedia Mobile Phones
Typical Application
VBAT
C_IN
4.7µF
EN_BACKLIGHT
EN_FLASH
RSET1
CT
RSET2
CREF
EN_LDO
C1
C2
1µF
1µF
C1+ C1- C2+ C2-
IN
OUT
AAT2842
BL1
IN
BL2
BENS
BL3
BL4
FENS
FL1
FL2
CT
BSET
FSET
FL3
FL4
OUTA
REF
FBA
OUTB
ENL
FBB
AGND PGND
C_OUT
2.2µF
R2B
R1B
VOUT LDOB
COUTB
VOUT LDOA
R2A
COUTA
R1A
2842.2006.10.1.0
1