Features
➤ Conservative and repeatable
measurement of available charge
in rechargeable batteries
➤ Designed for portable equipment
such as power tools with high discharge
rates
➤ Designed for battery pack integration
- 120μA typical standby current
(self-discharge estimation mode)
- Small size enables implementations
in as little as 1
2
square inch of PCB
➤ Direct drive of LEDs for capacity
display
➤ Self-discharge compensation using
internal temperature sensor
➤ Simple single-wire serial communications
port for subassembly
testing
➤ 16-pin narrow SOIC

General Description
The bq2011 Gas Gauge IC is intended
for battery-pack installation to maintain
an accurate record of available
battery charge. 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. The bq2011 is
designed for systems such as power
tools with very high discharge rates.
Battery self-discharge is estimated
based on an internal timer and temperature
sensor. Compensations for
battery temperature and rate of
charge or discharge are applied to
the charge, d i s charge, and
selfdischarge calculations to provide
available charge information across
a wide range of operating conditions.
Initial battery capacity is set using
the PFC and MODE pins. Actual
battery capacity is automatically
“learned” in the course of a discharge
cycle from full to empty and
may be displayed depending on the
display mode.
Nominal available charge may be directly
indicated using a five-segment
LED display. These segments
are used to indicate graphically the
nominal available charge.
The bq2011 supports a simple singleline
bidirectional serial link to an external
processor (common ground). The
bq2011 outputs battery information in
response to external commands over the
serial link. To support subassembly
testing, the outputs may also be controlled
by command. The external processor
may also overwrite some of the
bq2011 gas gauge data registers.
The bq2011 may operate directly
from four cells. With the REF output
and an external transistor, a simple,
inexpensive regulator can be built to
provide VCC from a greater number
of cells.
Internal registers include available
charge, temperature, capacity, battery
ID, and battery status.