a us t ria
m i c r o
s y s t e m s
AS3683
1A Backlight and Camera LED Power Charge Pump
P ro du c t B ri e f
1 General Description
The AS3683 is a low-noise, high-current 1A charge
pump designed for camera flash LEDs and LCD back-
lighting applications. The current sinks are capable of
driving up to 960mA of load current.
The AS3683 integrates two independent current source
blocks for driving a single flash LED (CURR
11
to
CURR
13
) with up to 480mA, and general purpose LEDs
(CURR
2
to CURR
4
) with up to 160mA/LED. The general
purpose LEDs are controlled individually and can be
used for backlighting, but also in support of an RGB fun-
light or a movie indicator lamp. To meet high-flash cur-
rent requirements (up to 960mA), both current source
blocks can be connected together (CURR
11
to CURR
13
and CURR
2
to CURR
4
).
The AS3683 utilizes austriamicrosystems's patent-pend-
ing Intelligent Adaptive Mode Setting (IAMS) to switch
between 1:1, 1:1.5, and 1: 2 modes. In combination with
very-low-drop-out current sinks, the device achieves
high efficiency over the full single-cell Li+ battery voltage
range. The charge pump operates at a fixed frequency
of 1MHz allowing for tiny external components and its
design ensures low EMI and low input-ripple.
The ultra-flexible brightness control scheme allows for
simple adaptation of the device to different system archi-
tectures.
In Softflash Mode the device is controlled by an I
2
C
interface. In these modes the LED brightness, flash
duration, GPIOs and various charge pump states are
controlled by internal register settings. The GPIO pins
can act as programmable input or output pins and can
also be set to trigger preview and flash light directly by a
camera module.
In Hardflash mode the LED brightness is controlled by
the Enable pins. These programming pins can be used
as simple enable pins, or as PWM input, again offering
ample flexibility for setting the LED brightness.
2 Key Features
!
High-Power 1A Charge Pump
- 1:1, 1:1.5, and 1:2 Intelligent Adaptive Mode Set-
ting (IAMS)
- Efficiency up to 95%
- Soft Start to Reduce Inrush Current
- Low-Noise Constant-Frequency Operation
Current Sinks
- 400mA Continuous Current (@V
IN
= 3.2 to 5V,
V
OUT
= 5V)
- Up to 960mA Pulsed Flash Current
- Programmable: 0 to 160mA, 0.625mA Resolution
Flexible Brightness Control
- Three 0 to 160mA LEDs
- Individually Addressable via I
2
C Interface
2 Operating Modes
- Softflash Mode (I
2
C Interface)
- Hardflash Mode (Dedicated Control Pins)
2 General Purpose Inputs/Outputs in Softflash Mode
- Digital Input, Output, and Tristate
- Programmable Pull-Up and Pull-Down
- Strobe Pin can be used for Camera Flash Control
LED Disconnect in Shutdown
Open LED Detection
Low Stand-By Current (6µA), Interface Fully
Operating
Low Shut-Down Current (0.2µA)
Wide Battery Supply Range: 3.0 to 5.5V
Thermal Protection
24-Pin, Small Form-Factor QFN Package
- 4 x 4 x 0.85mm, 0.5mm Pitch
- Enhanced Thermal Characteristics
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3 Application
Lighting management for cameras, mobile telephones,
PDAs, and other 1-cell Li+ or 3-cell NiMH powered
devices
.
© 1997-2005, austriamicrosystems AG, 8141 Unterpremstaetten, Austria-Europe. All Rights Reserved.
www.austriamicrosystems.com
Revision 1.0
1-4
AMSCO [ AUSTRIAMICROSYSTEMS AG ]
