BQ2014 Datasheet, PDF (3/22 Pages) Texas Instruments – Gas Gauge IC with External Charge Control

bq2014
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 RS in Figure 1).
A filter between the negative battery terminal and the
SR pin is required.
Figure 1. Battery Pack Application Diagram—LED Display,
3