Features

➤ Conservative and repeatable

measurement of available capacity

in Lithium Ion rechargeable

batteries

➤ Designed for battery pack integration

- 120μA typical operating

current

- Small size enables implementations

in as little as 1

2

square inch of PCB

➤ Integrate within a system or as a

stand-alone device

- Display capacity via singlewire

serial communication

port or direct drive of LEDs

➤ Measurements compensated for

current and temperature

➤ Self-discharge compensation using

internal temperature sensor

➤ 16-pin narrow SOIC

General Description

The bq2050 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 and rate of charge

or discharge are applied to the

charge, discharge, and self-discharge

calculations 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 bq2050

supports a simple single-line bidirectional

serial link to an external

processor (common ground). The

bq2050 outputs battery information

in response to external commands

over the serial link.

The bq2050 may operate directly

from one cell (VBAT > 3V). With the

REF output and an external transistor,

a simple, inexpensive regulator

can be built for systems with more

than one series cell.

Internal registers include available

capacity, temperature, scaled available

energy, 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 bq2050

power gauge data registers.