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.