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PDF AS3682 Data sheet ( Hoja de datos )
| Número de pieza | AS3682 | |
| Descripción | Camera Lighting Management Unit | |
| Fabricantes | austriamicrosystems | |
| Logotipo |  |
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austriamicrosystems
AS3682
480mA Camera Lighting Management Unit
Data Sheet
www.DataSheet4U.com
1 General Description
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 (CURR11 to CURR13) with up
to 480mA, and general purpose LEDs (CURR2 to
CURR4) 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 I2C 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 (@VIN = 3.2 to
5V, VOUT = 5V)
- 480mA Maximum Pulsed Flash Current
- Programmable: 0 to 160mA, 0.625mA Resolution
! Flexible Brightness Control
- Three 0 to 160mA LEDs
- Individually Addressable via I2C Interface
! Three Operating Modes
- Normal Mode (I2C Interface)
- Soft Flash Mode (I2C 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.
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1 page  
AS3682
Data Sheet
austriamicrosystems
www.DataSheet4U.com
Table of Contents
1 General Description ................................................................................................................................ 1
2 Key Features .......................................................................................................................................... 1
3 Applications ............................................................................................................................................ 1
4 Block Diagram ........................................................................................................................................ 2
5 Application Diagrams .............................................................................................................................. 2
6 Characteristics ........................................................................................................................................ 6
6.1 Absolute Maximum Ratings (Non-Operating) .................................................................................................. 6
6.2 Operating Conditions ....................................................................................................................................... 6
6.3 Electrical Characteristics ................................................................................................................................. 7
7 Typical Operation Characteristics ........................................................................................................... 9
8 Detailed Functional Descriptions .......................................................................................................... 11
8.1 Charge Pump ................................................................................................................................................ 11
8.1.1 Intelligent Adaptive Mode Switching (IAMS) ....................................................................................... 11
8.1.2 Soft Start ............................................................................................................................................. 11
8.1.3 Open LED Detection ........................................................................................................................... 11
9 Mode Settings ....................................................................................................................................... 12
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 CURR11, CURR12, CURR13 in Normal Mode and Soft Flash Mode ................................ 24
11.4 Control of CURR2, CURR3, CURR4 in Normal Mode and Soft Flash Mode ................................................ 29
11.5 Charge Pump Control Registers ................................................................................................................. 30
11.6 General Purpose Inputs/Outputs ................................................................................................................. 31
11.7 Power-On Reset .......................................................................................................................................... 32
11.8 Temperature Supervision ............................................................................................................................. 32
11.9 Serial Interface ............................................................................................................................................. 33
11.9.1 Features ............................................................................................................................................ 33
11.9.2 Device Address Selection ................................................................................................................. 33
11.9.3 Data Transfer Formats ...................................................................................................................... 33
11.9.4 Fixed ID Register .............................................................................................................................. 35
11.10 Register Map ............................................................................................................................................. 36
12 External Components ......................................................................................................................... 37
12.1 Capacitor and Resistor Selection ................................................................................................................ 37
12.2 Usage of PCB Wire Inductance ................................................................................................................... 37
12.3 External Component Specifications ............................................................................................................. 37
13 Pinout and Packaging ......................................................................................................................... 38
13.1 Hard Flash Modes Pin Descriptions .............................................................................................................. 38
13.2 Normal Mode and Soft Flash Mode Pin Descriptions .................................................................................. 39
13.3 Package Drawings and Markings ................................................................................................................ 40
14 Ordering Information ........................................................................................................................... 42
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AS3682
Data Sheet
austriamicrosystems
Charge Pump
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8 Detailed Functional Descriptions
8.1 Charge Pump
The AS3682 charge pump uses two external flying capacitors to generate output voltages higher than the battery volt-
age.
The charge pump can operate in three different modes:
! 1:1 Bypass Mode
- Battery input and output are connected by a low-impedance switch
- Battery current = output current
! 1:1.5 Mode
- The output voltage is 1.5 times the battery voltage (without load)
- Battery current = 1.5 times output current
! 1:2 Mode
- The output voltage is 2 times the battery voltage (without load)
- Battery current = 2 times output current
8.1.1 Intelligent Adaptive Mode Switching (IAMS)
The integrated charge pump determines the best compromise between the required LED supply voltage (Vf) and the
lowest internal power dissipation. The AS3682 examines the voltage at each current sink and automatically switches
into a higher charge pump mode; the switch-down procedure is achieved after the AS3682 performs analog signal pro-
cessing of all relevant parameters: the battery voltage, the actual charge pump voltage, the load current, and the resis-
tance of the next charge pump mode. By predicting the efficiency of the next state, the AS3682 will accurately
determine the switching point.
8.1.2 Soft Start
An implemented soft start mechanism reduces the inrush current. Battery current is smoothed when switching the
charge pump on and also at each switching condition. This precaution reduces electromagnetic radiation significantly.
8.1.3 Open LED Detection
The voltages at the current sinks are used to determine the mode switching of the charge pump up, thus an open wire
to the LED could lead to a to high-power dissipation of the circuit.
The AS3682 scans and compares all voltages on the current sinks continuously, so that if the charge pump is already
at 1:2 mode and the required current cannot be provided, the circuit stops that current sink sensing until the next
power-on condition. Using the circuit via the I2C interface (Normal Mode and Soft Flash Mode) the system can get
information on the failing path from the GPIO_output (page 31) register.
Scanning occurs automatically upon first entering 1:2 mode.
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| Páginas | Total 43 Páginas | |
| PDF Descargar | [ Datasheet AS3682.PDF ] | |
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