EDNE July 2012 - (Page 15)

Circuit Note CN-0235 Engineered and Tested. Ready to Integrate. Visit www.analog.com/CN0235 Devices Connected/Referenced AD7280A AD8280 ADuM5404 ADuM1400 Lithium Ion Battery Monitoring System Lithium Ion Battery Safety Monitor Quad-Channel Isolators with Integrated DC-to-DC Converter Quad-Channel Digital Isolators Fully Isolated Lithium Ion Battery Monitoring and Protection System EVALUATION AND DESIGN SUPPORT Circuit Evaluation Boards CN-0235 Circuit Evaluation Board (EVAL-CN0235-SDPZ) System Demonstration Platform (EVAL-SDP-CB1Z) can operate from a single wide supply range of 8 V to 30 V and operate over the industrial temperature range of −40°C to +105°C. The AD7280A contains an internal ±3 ppm reference that allows a cell voltage measurement accuracy of ±1.6 mV. The ADC resolution is 12 bits and allows conversion of up to 48 cells within 7 μs. The AD7280A has cell balancing interface outputs designed to control external FET transistors to allow discharging of individual cells and forcing all the cells in the stack to have identical voltages. The AD8280 functions independently of the primary monitor and provides alarm functions indicating out of tolerance conditions. It contains its own reference and LDO, both of which are powered completely from the battery cell stack. The reference, in conjunction with external resistor dividers, is used to establish trip points for the over/undervoltages. Each cell channel contains programmable deglitching (D/G) circuitry to avoid alarming from transient input levels. Design and Integration Files Schematics, Layout Files, Bill of Materials (zip file) CIRCUIT FUNCTION AND BENEFITS Lithium ion (Li-Ion) battery stacks contain a large number of individual cells that must be monitored correctly in order to enhance the battery efficiency, prolong the battery life, and ensure safety. The 6-channel AD7280A devices in the circuit shown in Figure 1 act as the primary monitor providing accurate voltage measurement data to the System Demonstration Platform (SDP-B) evaluation board, and the 6-channel AD8280 devices act as the secondary monitor and protection system. Both devices Figure 1. Lithium Ion Battery Monitoring and Protection System Simplified Schematic Rev. 0 Circuits from the Lab™ circuits from Analog Devices have been designed and built by Analog Devices engineers. Standard engineering practices have been employed in the design and construction of each circuit, and their function and performance have been tested and verified in a lab environment at room temperature. However, you are solely responsible for testing the circuit and determining its suitability and applicability for your use and application. Accordingly, in no event shall Analog Devices be liable for direct, indirect, special, incidental, consequential or punitive damages due to any cause whatsoever connected to the use of any Circuits from the Lab circuits. www.analog.com (Continued on last circuit note page) http://www.analog.com/AD7280A http://www.analog.com/AD8280 http://www.analog.com/ADuM5404 http://www.analog.com/CN0235 http://www.analog.com/ADuM1400 http://www.analog.com/AD7280A http://www.analog.com/EVAL-CN0235-SDPZ http://www.analog.com/EVAL-SDP-CB1Z http://www.analog.com/AD7280A http://www.analog.com/CN0235-DesignSupport http://www.analog.com/AD8280 http://www.analog.com/AD7280A http://www.analog.com/AD8280 http://www.analog.com

Table of Contents for the Digital Edition of EDNE July 2012

Cover
Contents
International Rectifer
Microchip
FTDI
Masthead
Comment
International Rectifer
Pulse
Analog Devices
Digi-Key
Analog Devices
Test & Measurement
Agilent Technologies
Baker's Best
Messe München
Understand and characterize envelope-tracking power amplifiers
Digi-Key
Cover Story
Coilcraft
Digi-Key
Signal Integrity
Altera
USB 3.0 : Bringing SuperSpeed connectivity to mobile devices
Digi-Key
Developing high-frequency integrated circuits for test and measurement
Design idea
Product Roundup
Tales from the cube

EDNE July 2012