Datasheet

Functional Description

General Operation

The bq2014 determines battery capacity by monitoring

the amount of charge input to or removed from a re

chargeable battery. The bq2014 measures discharge and

charge currents, estimates self-discharge, monitors the

battery for low-battery voltage thresholds, and compen

sates for temperature and charge/discharge rates. The

charge measurement is made by monitoring the voltage

across a small-value series sense resistor between the

battery’s negative terminal and ground. The available

battery charge is determined by monitoring this voltage

over time and correcting the measurement for the envi

ronmental and operating conditions.

Figure 1 shows a typical battery pack application of the

bq2014 using the LED display capability as a charge-

state indicator. The bq2014 is configured to display ca

pacity in a relative display mode. The relative display

mode uses the last measured discharge capacity of the

battery as the battery “full” reference. The LED seg

ments output a percentage of the available charge based

on NAC and LMD. A push-button display feature is

available for momentarily enabling the LED display.

The bq2014 monitors the charge and discharge currents

as a voltage across a sense resistor (see R

in Figure 1).

A filter between the negative battery terminal and the

SR pin is required.

bq2014

Figure 1. Battery Pack Application Diagram—LED Display,