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austriamicrosystems
General Description
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
2C 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
Key Features
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:
Improved thermal performance (ground = heat sink)
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
mode and I
2C mode)
Available in tiny WL-CSP Packages
3x4 balls 0.5mm pitch, 2x1.5mm package size
Application
Flash/Torch for mobile phones, digital cameras and PDA
Flash/Torch for mobile phones, digital cameras and PDA
AN3645 Demoboard
AS3645 ultra small high efficient single/dual LED flash driver with safety features
PRELIMINARY APPLICAT
ION NOTE
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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
AS3645 WLP DEMOBOARD V1.1: LAYOUT (TOP VIEW) ....................................................................................... 9
AS3645 WLP DEMOBOARD V1.1: LAYOUT (IN1 VIEW) ........................................................................................ 9
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
Parallel interface mode with adjustable output currents ..................................................................................................... 12
I²C Mode ......................................................................................................................................................................... 13
FREQUENTLY ASKED QUESTIONS ................................................................................................................... 15
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
Revision status
AS3645 Datasheet Rev.: 0v3.1
AN3645 Application note (this document): Rev.: 1v0
AS3645 WLP Demoboard schematic: Rev.: 1v1
AS3645 WLP Demoboard layout Rev.: 1v1
AS3645 Software version Rev.: 0v2
General description
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
The correct installed demo software can be started from
Start > Programs > austriamicrosystems AG > AS3645 Demosoftware.
USB connection and ASIC status are immediately indicated in the status bar of the demo software.
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AS3645 Connector, Jumper and Device locations
Listed below are the various connectors and jumpers.
Jumper
Function
Description
J1 USB Box Interface Connector
J2 GND
J3 Measurement pins EN1,EN2,Strobe,Torch,I2C_EN,GND
J4 two LEDs If this jumper is open, AS3645 will use 2 flash LEDs
J5 IND out 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 LED out This jumper opens the path from the pin LED_out to the flash LED
J8 Mode select I2C_EN connected to Vbat= I2C Interface
I2C_EN connected to GND= parallel interface with fixed output currents
I2C_EN connected to Rset= parallel interface with adjustable output currents
J9 TxMask This pin allows to lead a TxMask signal to pin I2C_EN
J10 GND
J11 to connect a pull up resistor to SDA Only used if I2C Interface is chosen (I2C_EN connected to Vbat)
J12 to connect a pull up resistor to SCL Only used if I2C Interface is chosen (I2C_EN connected to Vbat)
BU1 Positive battery supply Main battery supply
BU2 Negative battery supply Main battery ground
Device
Value
Description
U1 AS3645 Ultra Small High Efficiency 500mA DCDC boost white FLASH driver
C1 10µ F / 0603 / X5R Input capacitor
C2 10µ F / 0805 / X5R Output capacitor of the DCDC converter
L1 2.2uH Inductor FDSE0312-2.2uH
D1,D2 LWCSP9 Osram Flash LED
D3 Mini Top LED red Indicator LED
R4 26k Rset
R5 21k Rtxmask
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Connector and Jumper locations on AS3645 WLP Demoboard V1.1
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Application Schematic AS3645 Demoboard V1.1
Application Schematic AS3645 Demoborad V1.1
AS3645 WLP Demoboard V1.1: stackup
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AS3645 WLP Demoboard V1.1: Layout (top view)
Layout (top view)
AS3645 WLP Demoboard V1.1: Layout (IN1 view)
Layout (IN1 view)
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AS3645 WLP Demoboard V1.1: Layout (IN2 view)
Layout (IN2 view)
AS3645 WLP Demoboard V1.1: Layout (bottom view)
Layout (bottom view)
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AS3645 Interface modes:
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)
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)
This mode is selected by connecting the resistor Riset between I2C/EN and GND:
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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:
Basic functions:
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.
The “Write Register”-button can be used to write the values, which are selected in the GUI, to the IC. This is useful if the chip
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
using these control items, the registers of the IC are updated automatically.
Identification:
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
detected, is 400 mA. So if you set 500mA as flash current, the current through two LEDs will be 400mA.
Control settings:
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?
A: In case the control circuit (e.g. baseband) crashes while the flash LED is enabled. If there would be no timeout, the flash LED
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.
Q: Is there a smaller, lower cost solution available (even if AS3645 is already quite small)?
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,
Austria-Europe. Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted, merged,
translated, stored, or used without the prior written consent of the copyright owner.
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
obligation or liability to recipient or any third party shall arise or flow out of austriamicrosystems AG rendering of technical or
other services.
Contact Info
austriamicrosystems AG
Business Unit Communications
A 8141 Schloss Premstätten, Austria-EU
T. +43 (0) 3136 500-0
F. +43 (0) 3136 500-5692
info@austriamicrosystems.com
For local Sales Offices please see:
www.austriamicrosystems.com
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