Date: 15/03/2010

Lithium Ion battery monitoring ICs for high energy applications

Due to the high energy-density, Lithium-ion (Li-ion) batteries finding more use in high energy applications such as high-voltage energy, industrial and automotive applications which includes wind turbines, photo-voltaic cells, and hybrid electric vehicles. However Lithium Ion battery need to be monitored for electrical and heat parameters to ensure safety. For doing this Analog Devices is offering set of Li-ion battery monitoring and protection ICs to monitor voltage and current, signal isolation and safety monitoring.

Compared to NiMH (nickel-metal hydride) batteries, Li-ion batteries have a better energy-to-weight ratio, offer more efficient storage capacity over multiple charge-discharge cycles, and suffer less charge leakage when not in use. And unlike NiMH batteries traditionally used in high-voltage applications, battery stacks using Li-ion technology can comprise a large number of individual cells totaling hundreds of volts. Each cell must be properly monitored and balanced to ensure user safety, improve battery performance and extend battery life. ADI's Li-ion battery monitoring and protection ICs are designed for these requirements.

"Li-ion batteries must be treated with respect. Fires have occurred in notebook computer applications because over-voltage peaks were not monitored correctly," said Steve Sockolov, director, Precision Signal Processing group, Analog Devices. "Although the quality of battery fabrication has improved, guarding against higher temperature conditions in any energy, industrial or automotive application is critical. As one of the top suppliers to the energy, industrial and automotive industries, Analog Devices has the systems expertise and the right components to help customers with the design challenges associated with battery monitoring and safety."

ADI offering the below listed components required for a complete Li-ion battery monitoring and protection system:
Voltage measurement device - monitors and balances the cells (AD7280)
Current measurement device - monitors the cell stack's current (ADuC703x or AD821x)
Isolator - brings the measurement signals across the high-voltage barrier to the battery management unit (ADuM140x or ADuM540x)
Safety monitor - enables creation of a fail-safe circuit and safe environment to the user (AD8280)
Battery management unit - controls and manages battery functions to optimize operation (Blackfin ADSP-50x)

The new among the above is AD8280. The AD8280 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 - over-voltage, over-temperature or under-voltage. Other benefits include:
1. Extensive self-test upon prompt enhancing the designers ability to meet functional safety requirements such as ISO26262 and IEC61508.
2. Large, continuous range-of-trip point settings provide the flexibility to work with any Li-ion battery chemistry.
3. Flexible safety monitor configurations.
4. Communications daisy-chain option minimizes the need for isolators in a high-voltage cell stack.
5. Low-power mode enables the user to minimize battery drain when the battery is not in use.
6. Compliant with AEC-Q100 and EMI (electromagnetic interference) standards, making the part suitable for automotive applications.

The AD8280 Li-ion battery safety monitor is sampling now at $3.49 per unit in 1,000-unit shipments in a 48-lead LQFP (low-profile quad package).
For more info visit www.analog.com