BQ27421-G1 Datasheet, PDF (9/20 Pages) Texas Instruments – System-Side Impedance Track™ Fuel Gauge With Integrated Sense Resistor

bq27421-G1
www.ti.com
GENERAL DESCRIPTION
SLUSB85 – MAY 2013
The bq27421-G1 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).
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 bq27421-G1 control and status
registers, as well as its data locations. Commands are sent from system to gauge using the bq27421-G1’s I²C
serial communications engine, and can be executed during application development, system manufacture, or
end-equipment operation.
The key to the bq27421-G1’s high-accuracy gas gauging prediction is Texas Instrument’s proprietary Impedance
Track™ algorithm. This algorithm uses cell measurements, characteristics, and properties to create state-of-
charge predictions that can achieve high accuracy across a wide variety of operating conditions and over the
lifetime of the battery.
The bq27421-G1 measures charge/discharge activity by monitoring the voltage across a small-value sense
resistor. When a cell is attached to the bq27421-G1, cell impedance is computed, based on cell current, cell
open-circuit voltage (OCV), and cell voltage under loading conditions.
The bq27421-G1 uses an integrated temperature sensor for estimating cell temperature. Alternatively, the host
processor can provide temperature data for the bq27421-G1.
To minimize power consumption, the bq27421-G1 has several power modes: INITIALIZATION, NORMAL,
SLEEP, HIBERNATE and SHUTDOWN. The bq27421-G1 passes automatically between these modes,
depending upon the occurrence of specific events, though a system processor can initiate some of these modes
directly. More details are found in the bq27421-G1 Technical Reference Manual (SLUUAC5).
NOTE
Formatting Conventions in this Document:
Commands: italics with parentheses( ) and no breaking spaces, for example,
RemainingCapacity( ).
Data Flash: italics, bold, and breaking spaces, for example, Design Capacity.
Register bits and flags: italics with brackets [ ], for example, [TDA]
Data flash bits: italics, bold, and brackets [ ], for example, [LED1]
Modes and states: ALL CAPITALS, for example, UNSEALED mode.
Copyright © 2013, Texas Instruments Incorporated
Product Folder Links: bq27421-G1
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