The AS3682 is a low-noise, high-current charge pump
designed for camera flash LEDs and LCD backlighting
applications. The device is capable of driving up to
480mA of load current.
The AS3682 integrates two independent LED 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.
The AS3682 utilizes austriamicrosystems' 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 Normal and Soft Flash Modes 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 Hard Flash Mode, the LED brightness is controlled by
the Enable pins. Those programming pins can be used
as simple enable pins, as PWM input, again offering
ample flexibility for setting the LED brightness.
2 Key Features
!
High-Efficiency High-Power 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 Flash Current (@V
IN
= 3.2 to
5V, V
OUT
= 5V)
- 480mA Maximum 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
Three Operating Modes
- Normal Mode (I
2
C Interface)
- Soft Flash Mode (I
2
C Interface)
- Dedicated Control Pins for Hard Flash Modes
Two General Purpose Inputs/Outputs
- 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
!
!
!
!
!
!
!
!
!
!
!
3 Applications
Lighting management for cameras, mobile telephones,
PDAs, and other 1-cell Li+ or 3-cell NiMH powered
devices
.
www.austriamicrosystems.com
Revision 2.21
1 - 43
AS3682
Data Sheet
austriam
i c r o
systems
4 Block Diagram
Figure 1. AS3682 Block Diagram
V
2_5
22
AS3682
Digital
Supply
R
BIAS
23
2
V
BAT1
6
5
V
BAT2
C
2_P
Bandgap
and
Current
Reference
Charge Pump
1:1, 1:1.5, 1:2
7
3
C
2_N
C
1_P
ADR
1
24
4
C
1_N
CP_OUT
V
DD_GPIO
12
Digital
Part
CLK/P2
8
Mode
Selector
DATA/P1
9
Serial
Interface
Current Source
13
CURR
11
STROBE/F2
11
14
CURR
12
CURR
13
GPIO0/P0
10
15
SFL/F1
16
Current Source
T1/F0
17
19
CURR
2
20
HFL
18
21
CURR
3
CURR
4
GND
Exposed Pad
5 Application Diagrams
Figure 2. Normal and Soft Flash Mode Application Diagram
Battery
V
2_5
C3
1µF
R
BIAS
R1
240kΩ
7
V2.5 = 41
h
GND = 40
h
ADR
1
3
V
DD_GPIO
12
24
R4
1 - 10kΩ
4
C
1_N
CP_OUT
Flash &
Preview
13
STROBE/F2
11
CURR11
Camera C6
Flash 2.2µF
LED
C
1_P
C5
1µF
C
2_N
23
5
C
2_P
C4
1µF
22
2
V
BAT1
Feature
C1
2.2µF
Normal
Mode
I
2
C
Current
Sinks
3
Soft Flash
Mode
I
2
C
3
0 to 480mA
Block
6
V
BAT2
Interface
Total Current 0 to 450mA
Flash LEDs
Addressable
Strobe
Trigger
Strobe
Preview
Current
Sinks
Current per
Sink
Addressable
Block
STROBE/F2 STROBE/F2
or software or software
GPIO0/P0
or software
3
GPIO0/P0
or software
3
DATA/P1
9
AS3682
CLK/P2
8
General Purpose
LEDs (CURR2,
CURR3, CURR4)
0 to 37.5mA 0 to 160mA
Individual
Individual
14 CURR12
15
19
CURR13
CURR2
GPIO0/P0
SFL Mode:
SFL/F1 = V
DD_GPIO
Normal Mode:
SFL/F1 = GND
10
SFL/F1
16
Battery or
CP_OUT
T1/F0
HFL
17
18
20
CURR3
GND
21
CURR4
Exposed Pad
www.austriamicrosystems.com
Revision 2.21
2 - 43
AS3682
Data Sheet
austriam
i c r o
systems
Figure 3. Hard Flash Mode 1 Application Diagram
2
V
BAT1
Battery
Feature
Interface
Hard Flash Mode 1
Dedicated Control Pins
for Strobe (3x) &
Preview (3x)
V
2_5
C3
1µF
22
R
BIAS
23
6
V
BAT2
C1
2.2µF
Current Sinks
Total Current
Flash LEDs
Addressable
6
Strobe: 0 to 450mA
Preview: 0 to 400mA
Block
R1
240kΩ
ADR
1
5
C
2_P
C4
1µF
7
V
DD_GPIO
Selectable
DATA/P1
MSB Preview
CLK/P2
8
9
24
12
3
C
2_N
C
1_P
Strobe Trigger By Strobe Control Pins
C5
1µF
C
1_N
CP_OUT
Flash &
Preview
Strobe Preview
Current Sinks
By Preview Control
Pins
N/A
N/A
N/A
AS3682
4
Preview Control
(Active Low)
GPIO0/P0
LSB Preview
STROBE/F2
MSB Flash
SFL/F1
10
13
CURR11
Camera C6
Flash 2.2µF
LED
General Purpose
LEDs (CURR2,
CURR3, CURR4)
Current per
Sink
Addressable
11
14
15
CURR12
CURR13
CURR2
16
19
Strobe Control
(Active Low)
T1/F0
LSB Flash
Battery
HFL
17
20
CURR3
GND
18
21
CURR4
Exposed Pad
Figure 4. Hard Flash Mode 2 Application Diagram
Feature
Battery
V
2_5
C3
1µF
22
2
V
BAT1
Hard Flash Mode 2
Dedicated Control Pins
for Flash (3x) & General
Purpose (3x)
Interface
Current Sinks
C1
2.2µF
R
BIAS
23
6
V
BAT2
3
Flash: 0 to 450mA
Block
By Flash Control Pin
3
0 to 20/37.5mA
Block
Total Current
Flash LEDs
Addressable
Strobe Trigger
Strobe Preview
Current Sinks
General Purpose
LEDs (CURR2,
Current per Sink
CURR3, CURR4)
Addressable
R1
240kΩ
ADR
1
5
C
2_P
C4
1µF
7
V
DD_GPIO
12
3
C
2_N
C
1_P
DATA/P1
MSB Preview
CLK/P2
9
24
C
1_N
CP_OUT
Flash &
Preview
C5
1µF
8
AS3682
4
Backlight Control
(Active Low)
Selectable
GPIO0/P0
LSB Preview
STROBE/F2
MSB Flash
SFL/F1
10
13
CURR11
Camera
Flash
LED
C6
2.2µF
11
14
15
CURR12
CURR13
CURR2
16
19
Flash Control
(Active Low)
T1/F0
LSB Flash
Battery
HFL
17
20
CURR3
21
18
CURR4
GND
Exposed Pad
www.austriamicrosystems.com
Revision 2.21
3 - 43
AS3682
Data Sheet
austriam
i c r o
systems
Revision History
Revision
2.1
2.2
Date
10 February 2005
16 August 2005
Owner
ptr
ptr
Description
- Various minor updates implemented.
- Updated exposed pad size (D2 x E2).
- Updated parameter V
IH
max value.
- Updated parameter V
IL
max value.
- Added parameter V
POR_VBAT
min and max values.
- Added bit
Curr234_gpio0_ctrl
(page 29).
- Added bit
Curr234_strobe_ctrl
(page 29).
- Added Fixed ID Register (Addr: 15).
- Updated gpio0_pulls bit settings.
- Updated strobe_pulls bit settings.
- Updated data sheet status to public viewable.
2.21
6 July 2006
ptr
www.austriamicrosystems.com
Revision 2.21
4 - 43
AS3682
Data Sheet
austriam
i c r o
systems
Table of Contents
1 General Description ................................................................................................................................ 1
2 Key Features .......................................................................................................................................... 1
8.1.3 Open LED Detection ........................................................................................................................... 11
10 Hard Flash Modes .............................................................................................................................. 14
10.1 Hard Flash Mode 1 ...................................................................................................................................... 15
10.2 Hard Flash Mode 2 ...................................................................................................................................... 17
11 Normal and Soft Flash Modes ............................................................................................................ 19
11.1 Current Settings in Normal Mode ................................................................................................................ 20
11.2 Current Settings in Soft Flash Mode ............................................................................................................ 23
11.3 Timing Control of CURR
11
, CURR
12
, CURR
13
in Normal Mode and Soft Flash Mode ................................ 24
11.4 Control of CURR
2
, CURR
3
, CURR
4
in Normal Mode and Soft Flash Mode ................................................ 29
11.5 Charge Pump Control Registers ................................................................................................................. 30
11.6 General Purpose Inputs/Outputs ................................................................................................................. 31
11.8 Temperature Supervision ............................................................................................................................. 32
11.9 Serial Interface ............................................................................................................................................. 33
11.9.1
11.9.2
11.9.3
11.9.4
Features ............................................................................................................................................
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