General Description - Texas Instruments bq27441-G1 Technical Reference

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The bq27441-G1 battery fuel gauge accurately predicts the battery capacity and other operational

characteristics of a single, Li-based, rechargeable cell. It can be interrogated by a system processor to

provide cell information, such as state-of-charge (SOC). The device is orderable in two predefined

standard configurations:

•

The bq27441-G1A fuel gauge is predefined for LiCoO

voltage.

•

The bq27441-G1B fuel gauge is predefined for LiCoO

charge voltage.

Unlike some other Impedance Track™ fuel gauges, the bq27441-G1 cannot be programmed with specific

battery chemistry profiles. For many battery types and applications, the predefined standard chemistry

profiles available in the bq27441-G1A or bq27441-G1B fuel gauge are sufficient matches from a gauging

perspective.

Information is accessed through a series of commands, called Standard Commands. Further capabilities

are provided by the additional Extended Commands set. Both sets of commands, indicated by the general

format Command(), are used to read and write information contained within the control and status

registers, as well as its data locations. Commands are sent from the system to the gauge using the I

serial communications engine, and can be executed during application development, system manufacture,

or end-equipment operation.

The key to the high-accuracy, fuel gauging prediction is Texas Instruments proprietary Impedance Track™

algorithm. This algorithm uses cell measurements, characteristics, and properties to create SOC

predictions that can achieve high accuracy across a wide variety of operating conditions and over the

lifetime of the battery.

The fuel gauge measures the charging and discharging of the battery by monitoring the voltage across a

small-value, external sense resistor. Cell impedance is computed based on current, open-circuit voltage

(OCV), and cell voltage under loading conditions.

The fuel gauge uses an integrated temperature sensor for estimating cell temperature. Alternatively, the

system processor can provide temperature data for the fuel gauge.

To minimize power consumption, the fuel gauge has several power modes: INITIALIZATION, NORMAL,

SLEEP, HIBERNATE, and SHUTDOWN. The fuel gauge passes automatically between these modes,

depending upon the occurrence of specific events, though a system processor can initiate some of these

modes directly.