AAT2848 Datasheet, PDF (1/19 Pages) Advanced Analogic Technologies – High-Current Charge Pump For Backlight Display and Flash Applications

ChargePump^TM
PRODUCT DATASHEET
AAT2848
High-Current Charge Pump For Backlight Display and Flash Applications
General Description
The AAT2848 is a tri-mode charge pump optimized for
systems operating with lithium-ion/polymer batteries. The
charge pump provides power for both white LED backlight
and flash, with an integrated four channel backlight LED
current sink plus two channel flash LED current sinks.
Each backlight channel can drive up to 30mA, while each
flash current sink/channel can drive up to 300mA (600mA
total). Two independent S²Cwire™ (AnalogicTech’s Simple
Serial Control™) serial digital interface inputs enable,
disable, and set LED current to one of 32 levels for the
backlight and to one of 16 levels for the flash, with full-
scale current independently set for backlight and flash
using external resistors.
The AAT2848 offers a built-in fade-in/out function for
linear control of the backlight current during ON/OFF
transitions. The fade time is programmable by an exter-
nal capacitor.
The AAT2848 also offers a built-in flash timeout function
as a safety feature associated with the high power flash
driver. The safety timer is also programmable via an
external capacitor.
The AAT2848 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 AAT2848 is available in a Pb-free, space
saving TQFN33-20 package and operates over the -40°C
to +85°C ambient temperature range.
Features
• Tri-Mode (1x/1.5x/2x) Charge Pump
• Four 30mA Backlight LED Channels
• Independent S²Cwire Control for Backlight
• 32-Level Programmable Backlight Current Control—
Linear, Inverting
• Two 300mA Flash LED Channels
• Independent S²Cwire Control for Flash
• 16-Level Programmable Flash Current Control—
Linear, Inverting
• User-Programmable Full Scale Current for Backlight
and Flash
• User-Programmable Fade-In/Fade-Out Function for
Backlight
• User-Programmable Safety Timer for Flash LED
Protection
• Built-In Thermal Protection
• Automatic Soft-Start
• -40°C to +85°C Temperature Range
• Available in TQFN33-20 Package
Applications
• Camera Enabled Mobile Devices
• Digital Still Cameras
• Multimedia Mobile Phones
Typical Application
VBAT
CIN
4.7μF
S²Cwire
Backlight Control
S²Cwire
Flash Control
RBSET
15k
RFSET
14.3k
C1
C2
1μF
1μF
C1- C1+ C2- C2+
IN
OUT
AAT2848
BL1
BL2
BENS
BL3
FENS
BL4
FL1
BSET
FL2
FSET
WLEDs
OSRAM LW M673
or equivalent
COUT
2.2μF
Flash LEDs
Lumileds PWF1
or equivalent
CFLTMR
330nF
CFADE
47nF
FLTMR
FADE
AGND
PGND
2848.2008.05.1.0
www.analogictech.com
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