Features

➤ Accurate measurement of available

capacity in Lithium Ion batteries

➤ Provides a low-cost battery management

solution for pack

integration

- Complete circuit can fit in as

little as 1

2 square inch of PCB

- Low operating current (120μA

typical)

- Less than 100nA of data

retention current

➤ High-speed (5kb) single-wire

communication interface (HDQ

bus) for critical battery

parameters

➤ Monitors and controls charge FET

in Li-Ion pack protection circuit

➤ Direct drive of remaining capacity

LEDs

➤ Measurements automatically

compensated for rate and

temperature

➤ 16-pin narrow SOIC

General Description

The bq2050H Lithium Ion Power

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. These segments

are used to graphically indicate

available capacity. The

bq2050H also supports a simple

single-line bidirectional serial link

to an external processor (common

ground). The 5kb HDQ bus interface

reduces communications overhead

in the external microcontroller.

Internal registers include available

capacity, temperature, scaled available

energy, battery ID, battery

status, and Li-Ion charge FET

status. The external processor may

also overwrite some of the bq2050H

power gauge data registers.

The bq2050H 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.