FEATURES
Multifunction High-Accuracy Coulometric
Charge and Discharge Counter
Ideal for Portable Applications With
Nonremovable Rechargeable Battery Pack
Resolves Signals Less Than 12.5 μV
Internal Offset Calibration Improves Accuracy
128 Bytes of General-Purpose RAM
Internal Temperature Sensor Eliminates the
Need for an External Thermistor
High-Accuracy Internal Timebase Eliminates
External Crystal Oscillator
Low Power Consumption:
– Operating: < 80 μA
– Sleep: < 10 μA
Single-Wire HDQ Serial Interface
Packaging: 8-Lead TSSOP

DESCRIPTION
The bq26231 is a low-cost charge/discharge counter
peripheral in an 8-pin TSSOP. It works with an intelligent
host controller, providing state-of-charge information
for rechargeable Li-Ion, Li-Pol, or NiMH batteries. The
bq26231 measures the voltage drop across a low-value
series sense resistor between the negative terminal of
the battery and the battery pack ground contact. By
using the accumulated counts in the charge, discharge,
and self-discharge registers, an intelligent host
controller can determine battery state-of-charge
information. To improve accuracy, an offset count
register is available. The system host controller is
responsible for the register maintenance by resetting
the charge in/out and self-discharge registers as
needed.
The bq26231 features 13 bytes of registers, which
contain the capacity monitoring and status information.
The RBI input operates from an external power storage
source such as a capacitor or a series cell in the battery
pack, providing register nonvolatility for periods when
the battery is shorted to ground or when the battery
charge state is not sufficient to operate the bq26231.
During this mode, the register backup current is less
than 100 nA. Packaged in an 8-pin TSSOP, the
bq26231 is small enough to fit in the crevice between
two A-size cells or within the width of a prismatic cell.