Features
➤ Conservative and repeatable
measurement of available charge
in rechargeable batteries
➤ Charge control output operates an
external charge controller such as
the bq2004 Fast Charge IC
➤ Designed for battery pack integration
- 120μA typical standby current
➤ Display capacity via single-wire
serial communication port or direct
drive of LEDs
➤ Measurements compensated for
current and temperature
➤ Self-discharge compensation using
internal temperature sensor
➤ User-selectable end-of-discharge
threshold
➤ Battery voltage, nominal available
charge, temperature, etc.
available over serial port
➤ 16-pin narrow SOIC

General Description
The bq2014 Gas Gauge IC is intended
for battery-pack or in-system
installation to maintain an accurate
record of available battery charge.
The IC monitors the voltage drop
across a sense resistor connected in
series between the negative battery
terminal and ground to determine
charge and discharge activity of the
battery.
Self-discharge of NiMH and NiCd
batteries is estimated based on an
internal timer and temperature sensor.
Compensations for battery temperature
and rate of charge or discharge
are applied to the charge, discharge,
and self-discharge calculations
to provide available charge information
across a wide range of operating
conditions. Battery capacity
is automatically recalibrated, or
“learned,” in the course of a discharge
cycle from full to empty.
The bq2014 includes a charge control
output that controls an external
Fast Charge IC such as the bq2004.
Nominal Available Charge (NAC)
may be directly indicated using a
five-segment LED display.
The bq2014 supports a simple singleline
bidirectional serial link to an external
processor (with a common
ground). The bq2014 outputs battery
information in response to external
commands over the serial link.
Internal registers include available
charge, temperature, capacity, battery
voltage, battery ID, battery
status, and programming pin settings.
To support subassembly testing,
the outputs may also be controlled.
The external processor may
also overwrite some of the bq2014
gas gauge data registers.
The bq2014 may operate directly
from three or four cells. With the
REF output and an external transistor,
a simple, inexpensive regulator
can be built to provide VCC across a
greater number of cells.