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Lithium-ion battery protection circuit features safety monitor

March 5, 2010
Analog Devices Inc. addresses total system requirements with the unveiling of its integrated Li-ion battery protection circuit.

The development of lithium-ion (Li-ion) battery technology to meet the demanding storage and delivery requirements of energy, industrial, and automotive systems has spurred demand for safer, higher performing battery monitoring and protection circuits. Analog Devices Inc. addresses total system requirements with the unveiling of its integrated Li-ion battery protection circuit.

Li-ion batteries are an effective energy storage reservoir for wind turbines, photovoltaic cells, uninterruptible power supplies, and hybrid electric vehicles. Battery stacks using Li-ion technology can be comprised of a large number of individual cells totaling several hundred volts. Unlike batteries traditionally used in these high-voltage applications, each Li-ion cell must be properly monitored and balanced to ensure user safety, improve battery performance, and extend battery life.

Li-ion battery monitoring and protection systems require four major components:
• Voltage measurement device - monitors and balances the cells
• Current measurement device - monitors the cell stack’s current
• Isolators - brings the measurement signals across the high voltage barrier to the battery management unit
• Safety monitor - enables creation of a fail-safe circuit and safe environment to the user

With the introduction of the AD8280, Analog Devices provides the designer with the final piece needed to develop the complete front-end of a battery monitoring and protection circuit. The AD8280 is an integrated solution that monitors six cell voltages and two temperature inputs. It is powered completely from the battery stack, providing either a shared or a separate alarm for any of three conditions including over-voltage, over-temperature, or under-voltage. Other benefits include:
• Extensive self-test upon prompt, enhancing the designer’s ability to meet functional safety requirements such as ISO26262 and IEC61508
• Large, continuous range-of-trip point settings provide the flexibility to work with any Li-ion battery chemistry
• Flexible safety monitor configurations
• Communications daisy-chain option minimizes the need for isolators in a high-voltage cell stack
• Low-power mode enables the user to minimize battery drain when the battery is not in use
• Compliant with AEC-Q100 and EMI (electromagnetic interference) standards, making the part suitable for automotive applications

For more information, visit Analog Devices Inc., 3 Technology Way, Norwood, MA 02062. Phone: (800) 262-5643.


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