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8141 Unterpremstaetten, Austria
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AN3645 Demoboard
PRELIMINARY APPLICATION NOTE
AS3645 ultra small high efficient single/dual LED flash driver with safety features
General Description Key Features
The AS3645 is an inductive high efficient DCDC step up converter with two current sources. The DCDC step up converter operates at a fixed frequency of 2MHz and includes soft startup to allow easy integration into noise sensitive RF systems. The two current sources (one for driving one or two flash LEDs and one for the indicator
LED) can operate in flash / torch / assist (=video) light / indicator modes. If a two flash LEDs configuration is used, the LEDs are connected in series. Therefore identical current is guaranteed.
The AS3645 includes flash timeout, overvoltage, overtemperature, undervoltage and LED short circuit protection functions.
The AS3645 can be controlled either with parallel interface mode to allow simple integration.
Alternatively it can be controlled by I
2
C mode to allow a more sophisticated control of all settings like currents and timings.
The interface is selected by a dedicated pin (I2C/EN).
The AS3645 is available in a space-saving WL-CSP package measuring only 2x1.5mm and operates over the -30ºC to +85ºC temperature range.
Application Diagram
High efficiency 2MHz fixed frequency DCDC Boost converter with soft start allows small coils
- Stable even in coil current limit
High Flash LED(s) current (720mA for single flash LED,
1000mA (2x500mA) for dual flash LED)
Separate Indicator LED output
Flash LED(s) cathode connected to ground:
Simplified PCB layout
Flash, Torch, Assist and Indicator Mode
Protection functions:
Automatic Flash Timeout timer to protect the LED(s)
Overvoltage and undervoltage Protection
Overtemperature Protection
LED(s) short circuit protection
Dual Interface selectable by pin (parallel interface
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mode and I
2
C mode)
Available in tiny WL-CSP Packages
3x4 balls 0.5mm pitch, 2x1.5mm package size
Application
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Flash/Torch for mobile phones, digital cameras and PDA
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Flash/Torch for mobile phones, digital cameras and PDA
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Application Note AN3645
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Table of Contents
OTHER APPLICABLE DOCUMENTS AND PAPERS............................................................................................... 3
FURTHER APPLICATIONS ................................................................................................................................... 3
REVISION STATUS .............................................................................................................................................. 3
GENERAL DESCRIPTION ..................................................................................................................................... 3
GETTING STARTED ............................................................................................................................................. 4
AS3645 Demo Software Installation .................................................................................................................................... 4
Connecting the Demoboard and USB Box with the PC ......................................................................................................... 5
Starting the AS3645 Demo software.................................................................................................................................... 5
AS3645 CONNECTOR, JUMPER AND DEVICE LOCATIONS ................................................................................. 6
APPLICATION SCHEMATIC AS3645 DEMOBOARD V1.1 ...................................................................................... 8
AS3645 WLP DEMOBOARD V1.1: STACKUP ........................................................................................................ 8 valid
AS3645 WLP DEMOBOARD V1.1: LAYOUT (IN2 VIEW) ...................................................................................... 10
AS3645 WLP DEMOBOARD V1.1: LAYOUT (BOTTOM VIEW) ............................................................................. 10
AS3645 INTERFACE MODES: ............................................................................................................................ 11
Parallel interface mode with fixed output currents.............................................................................................................. 11
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ORDERING INFORMATION ................................................................................................................................ 16
COPYRIGHT....................................................................................................................................................... 16
CONTACT INFO ................................................................................................................................................. 16
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Other applicable documents and papers
Data Sheet: AS3645 0v3
Further Applications
Applications based on the AS3645 are continuously updated. Visit our home-page:
http: //www.austriamicrosystems.com
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Revision status
AS3645 Datasheet Rev.: 0v3.1
AN3645 Application note (this document): Rev.: 1v0
AS3645 WLP Demoboard schematic: Rev.: 1v1
AS3645 WLP Demoboard layout
AS3645 Software version
General description
Rev.: 1v1
Rev.: 0v2
Remark: all subsequent component numbering refers to the application schematics, shown in pt. Application Schematic.
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Getting Started
AS3645 Demo Software Installation
Start the demo software Installation with “AS3645_EvalSW_Setup.msi”.
Specify the installation folder.
The Install Shield will guide you through the rest of the installation.
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Connecting the Demoboard and USB Box with the PC
After the successful installation of the demo software, the USB Box can be connected to the PC and to the demoboard as shown in the picture below.
Starting the AS3645 Demo software
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Start > Programs > austriamicrosystems AG > AS3645 Demosoftware.
The correct installed demo software can be started from
USB connection and ASIC status are immediately indicated in the status bar of the demo software.
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Application Note AN3645
AS3645 Connector, Jumper and Device locations
Listed below are the various connectors and jumpers.
Jumper Function
Description
J1
J2
J3
J4
J5
USB Box Interface Connector
GND
Measurement pins two LEDs
IND out
EN1,EN2,Strobe,Torch,I2C_EN,GND
If this jumper is open, AS3645 will use 2 flash LEDs
This jumper opens the path from the pin IND_out to the indicator LED
J6 Mesurement pins GND,IND_out,LED_out,Vout,Vbat
J7
J8
J9
J10
J11
J12
BU1
BU2
U1
C1
C2
L1
D1,D2
D3
R4
R5
Device
26k
21k
GND
LED out
Mode select
TxMask
This jumper opens the path from the pin LED_out to the flash LED
I2C_EN connected to Vbat= I2C Interface
This pin allows to lead a TxMask signal to pin I2C_EN
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to connect a pull up resistor to SDA Only used if I2C Interface is chosen (I2C_EN connected to Vbat) to connect a pull up resistor to SCL
Positive battery supply
Negative battery supply
AS3645
Value
Main battery supply
Input capacitor
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Description
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10µ F / 0603 / X5R
10µ F / 0805 / X5R Output capacitor of the DCDC converter
2.2uH
LWCSP9
Mini Top LED red
Inductor FDSE0312-2.2uH
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Connector and Jumper locations on AS3645 WLP Demoboard V1.1
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Application Note AN3645
Application Schematic AS3645 Demoboard V1.1
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Application Schematic AS3645 Demoborad V1.1
AS3645 WLP Demoboard V1.1: stackup
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Application Note AN3645
AS3645 WLP Demoboard V1.1: Layout (top view)
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AS3645 WLP Demoboard V1.1: Layout (IN1 view)
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Layout (IN1 view)
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AS3645 WLP Demoboard V1.1: Layout (IN2 view)
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AS3645 WLP Demoboard V1.1: Layout (bottom view)
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Layout (bottom view)
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Application Note AN3645
AS3645 Interface modes:
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Parallel interface mode with fixed output currents
The output currents in parallel interface mode with fixed output currents are selected according to the following table:
(Datasheet page 12, table 4)
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This mode is selected by connecting the pin I2C/EN to GND:
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Parallel interface mode with adjustable output currents
The output currents in parallel interface mode with adjustable output currents are selected according to the following table:
(Datasheet page 12, table 5)
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Application Note AN3645
I²C Mode
Please find all set up options on page 13 of the Datasheet (Table 6: I2C Mode)
This mode is selected by connecting the pin I2C/EN to Vbat:
Also use J11 and J12 (pull up resistors on SDA, SCL)
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In this mode the AS3645 can be controlled and supervised using the demosoftware:
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Basic functions:
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With the button “Registers” the register table can be opened and all bits can be changed by clicking.
To refresh the register settings press the “Readout all Registers” button (thus refresh the values shown in the GUI), or check the checkbox “Register Polling” for an automatic periodical update of the register settings.
With the “Logfile”-button, the logfile can be opened in which the register changes, made in the current session, are logged. was reset and all register values should be updated according to the selected values in the GUI.
It isn’t needed to make changes take effect, which were made in the pull down menus or checkboxes. If changes are made by
Identification:
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In the “Identification”-field a fixed manufacture ID and mode ID, as well as the chip version are shown.
Fault detection:
Faults (register address 0x05h) in the application are indicated in the “Faults”-field. Green circles mark normal operation, a red circle marks a fault of the according part. In I2C mode, the fault bits are cleared by an I2C readout of the fault register.
LED Amount:
In the “LED Amount”-field, the LED Amount detection can be enabled and the number of LEDs is shown.
Also VREF Offset can be changed which is the LED detection threshold.
Current settings:
In the “current settings”-field, current values and the flash time out can be set. The highest flash current, if two LEDs are
Technical
In the “Control ”-field the flash, torch and indicator mode can be activated. Also the mode external torch mode can be set as output mode. If the “External Torch”-mode is selected as output mode, the torch-function can be activated by checking the checkbox “Extern Torch Mode”.
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Frequently asked questions
Q: What application is the AS3645 intended for?
A: Small size LED flash especially suitable for mobile phones using one or two flash LEDs.
Q: What are the most important features of the AS3645?
A: A small size inductive based flash driver with multiple interface and several safety features.
Q: How do I select the different control interface?
A: By connecting I2C/EN to GND or VBAT or connecting a resistor between I2C/EN and GND.
Q: What is TXMask?
A: TXMask is the reduction of the flash current, when the mobile phone RF-PA is operating at the same time in order not to exceed the total possible current from the battery.
Q: Why do I need a flash timeout timer?
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might be damaged due to overheating.
Q: Why do I need additional safety features?
A: During production the complete configuration should be verified. E.g. the coil fault detection of the AS3645 checks for a broken coil, the LED detection checks for an open or shorted LED. Furthermore the single/dual LED detection checks if one of the two flash LEDs is shorted.
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A: A charge pump based solution needs no coil (only small capacitors). See AS3685/86.
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Ordering information
Devices sold by austriamicrosystems AG are covered by the warranty and patent identification provisions appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are specifically not recommended without additional processing by austriamicrosystems AG for each application.
Copyright
Copyright © 2008, austriamicrosystems AG,
Schloss Premstaetten, A-8141 Unterpremstaetten, translated, stored, or used without the prior written consent of the copyright owner.
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The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However, austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No other services.
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Contact Info
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Business Unit Communications
A 8141 Schloss Premstätten, Austria-EU
T. +43 (0) 3136 500-0
F. +43 (0) 3136 500-5692 [email protected]
For local Sales Offices please see: www.austria
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