AMS AS3649 is a high-current LED flash driver capable of delivering up to 2500mA of current to power demanding LEDs. It features an integrated charge pump for fast charging of external capacitors, enabling short flash times and high peak currents. The device also includes various protection features such as over-current, over-voltage, and over-temperature protection to ensure safe operation. With its compact size and low power consumption, the AMS AS3649 is ideal for use in space-constrained applications such as mobile phones and digital cameras.
AMS AS3649 is a high-current LED flash driver capable of delivering up to 2500mA of current to power demanding LEDs. It features an integrated charge pump for fast charging of external capacitors, enabling short flash times and high peak currents. The device also includes various protection features such as over-current, over-voltage, and over-temperature protection to ensure safe operation. With its compact size and low power consumption, the AMS AS3649 is ideal for use in space-constrained applications such as mobile phones and digital cameras.
www.ams.com
Revision 1.1 / 2012/07/21
Application Note: AN01 – AS3649
2500mA High Current LED Flash Driver
AS3649
2500mA High Current LED Flash Driver
strictly confidential
AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
page 1/20
Table of Contents
1.
General Information ............................................................................................................... 2
2.
Revision Status ...................................................................................................................... 2
3.
Getting Started ...................................................................................................................... 3
4.
Board Startup ........................................................................................................................ 5
5.
Hardware Overview ............................................................................................................. 10
6.
GUI – Software .................................................................................................................... 12
7.
PCB Layer Stackup ............................................................................................................. 17
8.
AS3649 Demoboard1V1 Schematic .................................................................................... 18
9.
Layout (Top View) ............................................................................................................... 19
10.
Layout (Bottom View) .......................................................................................................... 19
1.1.
Application .................................................................................................................
2
3.1.
Evaluation Software Installation ................................................................................. 3
3.2.
Connecting the Demoboard ....................................................................................... 3
3.3.
Starting the Software ................................................................................................. 4
4.1.
Automatic Readout of Fault Indications ..................................................................... 5
4.2.
Indicator Mode\PWM ................................................................................................. 6
4.2.1.
Application ............................................................................................................. 6
4.2.2.
Operation ............................................................................................................... 6
4.3.
Torch Light ................................................................................................................. 7
4.3.1.
Application ............................................................................................................. 7
4.3.2.
Operation ............................................................................................................... 7
4.4.
Flash Mode ................................................................................................................ 8
4.4.1.
Operation ............................................................................................................... 8
5.1.
AS3630 Demoboard1V2 Jumper and Device Locations ...........................................10
6.1.
Updating the USB-Box ..............................................................................................12
6.2.
GUI Overview ............................................................................................................13
6.2.1.
Operation Mode ....................................................................................................14
6.2.2.
Indicator Mode ......................................................................................................14
6.2.3.
NTC .......................................................................................................................14
6.2.4.
Miscellaneuos .......................................................................................................16
6.2.5.
ADC.......................................................................................................................16
6.2.6.
External Strobe and Flash Timings .......................................................................16
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
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Copyright ..................................................................................................................................... 20
Disclaimer ................................................................................................................................... 20
1. General Information
1.1. Application
Flash/Torch for mobile phones.
2. Revision Status
Application Note Rev.: AN01
Layout Rev.: 1v1
Schematic Rev.: 1v1
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
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3. Getting Started
3.1. Evaluation Software Installation
Install the AS3649 Evaluation Software, which can be found on the USB-stick from the demokit.
3.2. Connecting the Demoboard
Follow the sequence to connect the AS3630 board (as shown in the picture below):
1. Connect the ams AG USB-BOX
2. Connect the battery to VBAT and GND
3. Turn the board on with the Enable switch
Figure 1:
Hardware setup
Hardware setup of the AS3649 demoboard.
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
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3.3. Starting the Software
The correctly installed demo software can be started from Start > Programs > ams > AS3649 or
from the computer’s desktop.
Figure 2:
Evaluation Software
Start-up window of the evaluation software GUI
Under “Settings” enable “Enable Chip Detection”.
USB connection is immediately indicated in the status bar of the demo software.
Figure 3:
Evaluation Software
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
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USB and demoboard connection indicators
4. Board Startup
• Check first if battery is charged!
• Connect Battery (~3.7V Lithium Ion) to VBAT.
• Connect USB Box.
• Turn on the Enable switch.
• Activate Status Polling
• Press the “Readout Registers”-button
• Press “Settings” an “ Enable Chip Detection”
Figure 4:
Readout Registers Button
• If the AS3649 demoboard is supplied and connected correctly to the USB-Box, the indicators on
the bottom right of the GUI will show the words “USB” and “AS3649 Rev.1” in green.
Figure 5:
Status Bar
4.1. Automatic Readout of Fault Indications
Therefor go to the tab “settings” and activate automatic update. The software is now always
updating the Fault & Status Indications. If an Indication gets highlighted it must be reset
manually.
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
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Figure 6:
Faulst and Status indications
4.2. Indicator Mode\PWM
4.2.1. Application
Most times a red LED is used as Indicator in mobilephones.
In some countries it is a law to warn people before a picture is made or if somebody is using the
automatic release the LED starts blinking faster before it picture is made.
4.2.2. Operation
• Select the checkbox ‘Indicator’. The LEDs will be lightning.
Figure 7:
Indicator Mode/PWM Checkbox
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Preliminary Application Note: 2500mA High Current LED Flash Driver
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4.3. Torch Light
4.3.1. Application
It can be used as torch function in an mobilephone or as autofocus infront of a flash
4.3.2. Operation
• Select the desired Current and enable the Torch operation
• Figure 8:
Flash Timings Settings
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Preliminary Application Note: 2500mA High Current LED Flash Driver
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4.4. Flash Mode
4.4.1. Operation
• Select the desired flash time in the ‘Flash Timings’ settings. If a high current is selected the
flash time has to be limited to 100ms to prevent the LED of thermal damage.
• Enable charge SC. The Supercap will charge to a certain value.
Figure 9:
Flash time
Figure 10:
Flash Timings Settings
Disable the checkbox ‘Enable’ in the ‘External Strobe’ settings
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
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• Click on the checkbox ‘Flash Mode’ in the ‘Operation Mode’ settings to trigger a flash.
Figure 11:
Flash Mode Checkbox
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
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5. Hardware Overview
5.1. AS3630 Demoboard1V2 Jumper and Device Locations
Figure 12:
Jumper Locations
Jumper Function Jumper setting Comment
J1 GND
J2 General purpose
measurement pinhead
J4 VOUT Measurement pinhead
J5 USB Box Interface
Connector I2C-IF
J6 Enable LED Yes Enabling LED2 ( can be used
for current measurements)
J7 Mode Selector Yes
Selecting Dual or Single LED
application
J8 LED Out 2 Measurement pinhead
J10 LED Out 1 Measurement pinhead
J7;J9 LED connection Pin
S1 Strobe switch Optional strobe function
S2 Torch switch Optional torch function
S4 On/off switch
BU1 VBAT
BU2 GND
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
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Figure 13:
Device Specifications
Device Value Comment
C1 100uF Optional
C2 10uF Input capacitor: GRM188R60J106UE82, Murata
C4 10uF Output capacitor: GRM219R61A116U, Murata
C5 100nF optional
L1 1uH Coil DCDC1: LQM32ON1R0MGO
D1, D2
U1 AS3630 6A SuperCap Flash Driver with Torch and Indicator
Figure 14:
Connector and Jumper Locations
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
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6. GUI – Software
6.1. Updating the USB-Box
• Connect the USB-Box (J5) with the PC and start the AS3630 Demo Software.
• When connecting the USB-Box for the first time, the box has to be updated to the new Version.
• The update can be started by selecting ‘Firmware Upgrade’ from the Help menu.
Figure 15:
USB-Box Firmware Upgrade
• Select the folder ‘USBBox_Firmware and execute the file ‘usbbox.hex’.
Figure 16:
USB-Box Firmware Upgrade – File Destination
Figure 17:
USB-Box Firmware Upgrade – HEX File
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
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6.2. GUI Overview
Write into registers:
Read from registers:
Figure 18:
GUI Description Page 1:
Operation Mode:
See below
TXMask Register:
• TXMask Mode
o This function reduces the flash current in case of
parallel operation to a RF amplifier and avoids a
system shutdown
• External torch mode
o Enable external torch function without I2C.
•
NTC
See below
LED Current settings:
• Indicator PWM:
Selecting current PWM duty cycle
• LED Currents:
Output current for Indicator, Torch
Light and Flash Mode
• Link LED1 & LED2:
Combines Output currents in the SW
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
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GUI Description Page1 Continued
6.2.1. Operation Mode
• Shutdown:
The AS3630 is in Shutdown mode
• Indicator operation:
Activates the indicator mode or Indicator PWM operation
• Torch operation:
Activates the torch mode up to 247mA each current source
• Falsh Op.:
Enables the Flash mode up 1,25A each current source
6.2.2. Indicator Mode
The Indicator mode normally is working with a PWM function because at such low currents no
LED is defined. To receive the right Indicator current a higher current is used and the LED
current is just the PWM current ( like 1/16).
6.2.3. NTC
The flash LED is protected by the AS3649 using an internal comparator connected to
NTC and an current source to measure the LED temperature. If once it is triggered, the DCDC is
stopped, the current sources are disabled.
As the external NTC cannot measure the LED temperature in real time during a high current flash
pulse (the duration from heating up of the LED until the NTC recognizes a too hot LED is usually too
long), it is advisable to measure the LED temperature before the flash pulse and judge how much
current can be driven through the LED.
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
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Figure 19:
GUI Description Page1 Continued
Diagnostic Pulse
:
• Current Reduction by VIN
measurements in Flash
Mode and Diagnostic
Pulse
Please look it up in
the specified
Appnote!!
Miscellaneous
:
See below
Fault & Status Indication:
• Indication for all safety und features and status information
o If an Indication is set, you have to reset it manually
ADC:
See below
External
Strobe:
Flash
Timings
See below
LED Output Voltage Level:
• Shows actual and minimum
LED current
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
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6.2.4. Miscellaneuos
• Frequency switching 4MHz / 1MHz
If the frequency switching DCDC converter always operates in PWM mode (exception: PFM mode
is allowed during startup) to reduce EMI in EMI sensitive systems. For high duty cycles close to
100% on-time (maximum duty cycle) of the PMOS, the DCDC converter can switch into a 1MHz
operating mode and maximum duty cycle to improve efficiency for this load condition4. The DCDC
converter returns back to its normal 4MHz operating frequency when load or supply conditions
change. Due to this switching between two fixed frequencies the noise spectrum of the system is
exactly defined and predictable. If improved efficiency is required, the fixed switching between
4MHz / 1MHz can be disabled.
• Balancer Force on
To improve the efficiency of the AS3649 for LEDs with unmatched forward voltage and reduce the
internal power dissipation. This balancer can change the currents through the LEDs by up to +/-
15% to match the forward voltage of the LED.
• Skip Enable:
Allow Pulseskip operation for ILED
6.2.5. ADC
The internal ADC is used to monitor LED temperature and DIE temperature.
6.2.6. External Strobe and Flash Timings
• External Strobe:
Enables external Strobe Pin, used in Flash Mode.
• Flash Timings:
Set the flash time or limit the external strobe through this time
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
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7. PCB Layer Stackup
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Preliminary Application Note: 2500mA High Current LED Flash Driver
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8. AS3649 Demoboard1V1 Schematic
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AS3649 – AN01 – Demoboard
Preliminary Application Note: 2500mA High Current LED Flash Driver
www.ams.com Revision 1.1 / 2012/07/21
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9. Layout (Top View)
10. Layout (Bottom View)
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AMS AS3649 is a high-current LED flash driver capable of delivering up to 2500mA of current to power demanding LEDs. It features an integrated charge pump for fast charging of external capacitors, enabling short flash times and high peak currents. The device also includes various protection features such as over-current, over-voltage, and over-temperature protection to ensure safe operation. With its compact size and low power consumption, the AMS AS3649 is ideal for use in space-constrained applications such as mobile phones and digital cameras.
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