Features
➤ Accurate measurement of available
capacity in NiCd or NiMH
batteries
➤ Low-cost battery management solution
for pack integration
- As little as 1
2 square inch of
PCB for complete circuit
- Low operating current (120μA
typical)
- Less than 100nA of data
retention current
➤ High-speed (5kb/s) single-wire
communication interface (HDQ
bus) for critical battery
parameters
➤ Communication with an external
charge controller such as the
bq2004
➤ Direct drive of remaining capacity
LEDs
➤ Automatic rate and temperature
compensation of measurements
➤ 16-pin narrow SOIC

General Description
The bq2014H NiCd/NiMH Gas
Gauge IC is intended for batterypack
or in-system installation to
maintain an accurate record of
available battery capacity. The IC
monitors a 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. Compensations for battery
temperature, self-discharge,
and rate of discharge are applied to
the charge counter to provide available
capacity 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.
Nominal available capacity may be
directly indicated using a fivesegment
LED display. The bq2014H
also supports a simple single-line
bidirectional serial link to an external
processor (common ground). The
5kb/s HDQ bus interface reduces
communications overhead in the
external microcontroller.
Internal registers include available
capacity and energy, temperature,
voltage and current, and battery
status. The external processor may
also overwrite some of the bq2014H
gas gauge data registers.
The bq2014H can operate from the
batteries in the pack. The REF output
and an external transistor allow
a simple, inexpensive voltage regulator
to supply power to the circuit
from the cells.