Application Note: AS8506-AN03 – Active Balancer AS8506 AN03 – Active Balancer www.ams.com Revision 1.0 / 07/10/13 page 1/13 AS8506-AN03 Active Balancer Table of Contents 1 General Description ............................................................................................................. 3 1.1 Kit Content ........................................................................................................................... 3 2 Getting Started ..................................................................................................................... 3 3 Hardware Description........................................................................................................... 4 4 Configuration ........................................................................................................................ 5 4.1 Number of cells .................................................................................................................... 5 4.2 Configuration of VREF ......................................................................................................... 5 4.3 Configuration of master/slave .............................................................................................. 6 4.4 Configuration of Active Balancing source ............................................................................ 6 5 Software Description ............................................................................................................ 7 6 Board Schematics, Layout and BOM ................................................................................. 10 7 Ordering Information .......................................................................................................... 13 Revision History Revision Date Owner Description 1.0 07.10.2013 gheh Initial release 1.1 09.09.2014 gheh Added placement of R23 for no optocoupler option www.ams.com Revision 1.0 / 07/10/13 page 2/13 AS8506-AN03 Active Balancer 1 General Description This document describes the AS8506 Active Balancer Demo. This kit demonstrates the AS8506 in conjunction with a host controller. Each board allows you to balance up to 7 cells and multiple boards can be connected to support higher cell counts. The hardware will support li-based cell packs as well as EDLCs. Number of cells, target voltage as well as over and under voltage can be configured via a GUI 1.1 Kit Content The kit consists of one double layer board with an 8 pin battery connector two stack connectors and a mini HDMI port to interface to the host controller and a mini-HDMI to micro-HDMI cable. Figure 1: AS8506 Active Board 2 Getting Started To get started configure the device to your cell count and voltage specifications as described in chapter 4. Also if you plan to connect multiple boards in a stack configure them as described in Section 4.3. After having set up the hardware install the software that can be downloaded from: www.ams.com/DK-ActiveBoard www.ams.com Revision 1.0 / 07/10/13 page 3/13 AS8506-AN03 Active Balancer Once finished with the installation connect the batteries to the boards, connect the master board via the provided HDMI cable to the USB Interface board and connect that to a PC via USB. You also need to provide power to the active balancer. This is described in section 4.4. Afterwards start the PC GUI. You should be all set to explore the possibilities of the chipset via the GUI interface. As described in Section 5 3 Hardware Description The AS8506 Active demo is powered via the battery connected via J1. Unconnected pins (in case lower cell counts then 7 are used) are shorted out by the bridging resistor and can be left unconnected. B E A C D Figure 2: PCB Top Side Diagram Label Name Designator Description Info A BATT J1 Battery Connector Connects to 3 to 7 cells GND on the bottom B TOP_CONN J2 Top Connection To stack multiple boards C BOT_CONN J3 Bottom Connection To stack multiple boards and connect the active supply for the balancing D AMS_HDMI J4 Master Connection Connects to the USB Interface Board via provided cable E TEMP J5 Temp Sensor Can be connected to external temp sensor Table 1: Connection Diagram www.ams.com Revision 1.0 / 07/10/13 page 4/13 AS8506-AN03 Active Balancer Figure 3: PCB Bottom Side Diagram 4 4.1 Configuration Number of cells Minimum number of cells to be balanced is 3 or as many to reach a battery voltage of at least 6V (cell chemistry / technology dependent). A maximum of 7 cells can be balanced by this board! Remove zero ohm resistors according to table: Cell-Nr Remove 3 none 4 R4 5 R4, R3 6 R4, R3, R2 7 R4, R3, R2, R1 Table 2: Cell Adjust 4.2 Configuration of VREF There are two options to set the balancing target voltage: 1. Defined by DAC via the GUI configuration interface 2. Defined by external voltage divider (has to be activated in the GUI) In case the second option is chosen or if you want to switch between the options the divider R13, R14 needs to be selected according to number of cells according to the following table: www.ams.com Revision 1.0 / 07/10/13 page 5/13 AS8506-AN03 Active Balancer Cell-Nr R14 R13 3 100K 200K 4 100K 300K 5 30K 120K 6 150K 750K 7 20K 120K Table 3: VREF relative adjust 4.3 Configuration of master/slave If you want to chain multiple devices you have to configure the chained devices into slave mode and unsolder the stack termination registers from all but the topmost board Multiple devices can be connected via J2 and J3 which just plug together. The lowest board always has to be the master. Meaning this board has to be configured as master (which is the factory setting) and this board is the one to connect to the USB Interface box. To configure a board for slave mode you have to move the 0Ω Resistor R10 to R9. Then you have to unsolder R5, R7 and R8 termination resistors from all but the topmost board. 4.4 Configuration of Active Balancing source Per default the board is configured to take the power for active balancing from an external 5V Supply connected to Pins 1&2 of the J3 Bottom Connector where Pin 1 is GND and Pin 2 is +5V. This 5V Supply is fed through the whole stack and allows you to balance the Cells from this external supply. If only one module is used the Optocoupler can be disabled by moving R25 to R23 and moving R26 to R21. There is also a provision to power the Flyback converter from the battery pack voltage. (Place R18/R23 instead of R19/R24) This however requires changing the transformer as it was calculated with 5V as input voltage. The Wuerth Component Selector (http://www.weonline.com/web/en/passive_components_custom_magnetics/toolbox_pbcm/Component_Selector_2 .php) allows you to recalculate the settings for the transformer. On the board we use a WE-FLEX 749196111 type. www.ams.com Revision 1.0 / 07/10/13 page 6/13 AS8506-AN03 Active Balancer 5 Software Description Figure 4: AS8506 GUI Once started the PC GUI will automatically detect the AS8506 Boards connected to the USB Interface and enumerate those. The number of Cells will be displayed under “Cells found” and the number of Boards under “Boards found” The GUI allows you to configure all settings of the AS8506 Chip. The configuration can be either done via practical dropdown menus on the right-hand side in the Settings section or directly to the registers by clicking on Register Map and manipulating the registers in a bitwise fashion. All settings display a ToolTip if you hover over the settings with your mouse for a second. Depending on the transformer you are using und the supply voltage as well as the current you require for balancing you can manipulate the PWM Frequency and Duty Cycle of the active balancing boards. Keep in mind that if you exceed the 100mA continuous current the chip can handle it may die due to electrical overstress or overheat. The default settings should work in normal cases. www.ams.com Revision 1.0 / 07/10/13 page 7/13 AS8506-AN03 Active Balancer The settings should be pretty self-explanatory but keep in mind to set the correct lower and upper thresholds and reference if you’re using the DAC and activate the internal reference and thresholds in the checkboxes to the right: Figure 5: Reference and threshold setting All status information from the boards can by dynamically updated by activating the Automatic Update Feature under Settings. This will update ADC values as well as Over-voltage Under-voltage, Zero-cross, and Reference Status Information of each board connected every 2 seconds. Once the balance process is started update rate will drop to every minute because the chip has to stop its balancing cycle to update the ADC and that should not happen too often. Figure 6: Automatic Update Feature Also the Enable Chip Detection checkbox allows you to detect when AS8506 Boards have been unplugged from the Interface and reconnected. Last but not least the Button allows you to activate the balance feature at will. Green button means balance is active. Gray means not active. Balance Done LED will light green as soon as the balance process has finished and Cell Voltage or Temp not OK Led will light if the batteries exceed the set boundary limits. www.ams.com Revision 1.0 / 07/10/13 page 8/13 AS8506-AN03 Active Balancer In addition to this Tab there is a graphing tab which gives a graphical representation of the cell voltages and allows you to log the measured voltages to a file. Figure 7: Graphing Tab The Log to File button will open a file dialog which selects where the .csv log file will be saved. From then on data that is acquired via the auto update function will automatically be logged to that file. The Autoscale checkbox will automatically zoom in on the cell data. Also the window can be zoomed with the mouse wheel and moved with the left mouse button. www.ams.com Revision 1.0 / 07/10/13 page 9/13 AS8506-AN03 Active Balancer 6 Board Schematics, Layout and BOM Figure 8: Schematic www.ams.com Revision 1.0 / 07/10/13 page 10/13 AS8506-AN03 Active Balancer Figure 9: Top Layer Figure 10: Bottom Layer www.ams.com Revision 1.0 / 07/10/13 page 11/13 AS8506-AN03 Active Balancer Figure 11: BOM www.ams.com Revision 1.0 / 07/10/13 page 12/13 AS8506-AN03 Active Balancer 7 Ordering Information The AS8605 Active Balancer demo can be ordered via: Table 4: Ordering Information Ordering Code Productname AS8506-DK-ACTIVE AS8506 Active Balancer Board Materialnumber Copyright Copyright © 1997-2013, ams AG, Tobelbader Strasse 30, 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. All products and companies mentioned are trademarks or registered trademarks of their respective companies. www.ams.com Revision 1.0 / 07/10/13 page 13/13