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.