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.