Lithium-ion (Li-ion) batteries are growing in popularity as energy storage
reservoirs for high-voltage energy, industrial and automotive applications,
such as wind turbines, photo-voltaic cells, and hybrid electric vehicles,
and this has spurred demand for safer, higher performing battery monitoring
and protection systems. Analog Devices (ADI) has addressed the requirements
of Li-ion battery manufacturers and power system designers with the
unveiling today of a new Li-ion battery monitoring and protection system
that integrates all necessary components, including voltage and current
measurement, 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 totalling hundreds of volts. Each cell must be
properly monitored and balanced to ensure user safety, improve battery
performance and extend battery life. ADI's new Li-ion battery monitoring and
protection system performs these functions while also allowing power system
designers to replace costly discrete components, decrease power consumption
and reduce system space, says the company.
"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 offers the main 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 Li-ion battery monitoring and protection system includes a safety
monitor, the AD8280. The new safety monitor provides the designer with the
final piece needed to develop the complete front-end of a battery monitoring
and protection system. 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 - over-voltage, over-temperature or under-voltage. Other
benefits include: Extensive self-test upon prompt enhancing the designers
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.
The AD8280 Li-ion battery safety monitor is available in a 48-lead LQFP
(low-profile quad package), says the company.
