
Features
Conservative and repeatable
measurement of available charge
in rechargeable batteries
Designed for portable equipment
such as power tools with high dis-
charge rates
Designed for battery pack inte-
gration
-
120
μ
A typical standby current
(self-discharge estimation mode)
-
Small size enables imple-
mentations in as little as
12
square inch of PCB
Direct drive of LEDs for capacity
display
Self-discharge compensation us-
ing internal temperature sensor
Simple single-wire serial commu-
nications port for subassembly
testing
16-pin narrow SOIC
General Description
The bq2011 Gas Gauge IC is intended
for battery-pack installation to main-
tain an accurate record of available
battery charge. The IC monitors a
voltage drop across a sense resistor
connected in series between the nega-
tive battery terminal and ground to
determine charge and discharge ac-
tivity of the battery.
designed for systems such as power
tools with very high discharge rates.
The bq2011 is
Battery self-discharge is estimated
based on an internal timer and tem-
perature sensor. Compensations for
battery temperature and rate of
charge or discharge are applied to
the charge, discharge, 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.
battery capacity is automatically
“l(fā)earned” in the course of a dis-
charge cycle from full to empty and
may be displayed depending on the
display mode.
Actual
Nominal available charge may be di-
rectly indicated using a five-seg-
ment LED display. These segments
are used to indicate graphically the
nominalavailablecharge.
The bq2011 supports a simple single-
line bidirectional serial link to an exter-
nal 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 con-
trolled by command. The external proc-
essor may also overwrite some of the
bq2011gasgaugedataregisters.
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 V
CC
from a greater number
of cells.
Internal registers include available
charge, temperature, capacity, battery
ID,and battery status.
1
Gas Gauge IC for
High Discharge Rates
2/96 E
Pin Connections
Pin Names
1
PN201101.eps
16-Pin Narrow SOIC
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
VCC
REF
NC
DQ
RBI
SB
DISP
SR
MODE
SEG1
SEG2
SEG3
SEG4
SEG5
PFC
VSS
MODE
Display mode output
SEG
1
LED segment 1
SEG
2
LED segment 2
SEG
3
LED segment 3
SEG
4
LED segment 4
SEG
5
LED segment 5
PFC
Programmed full count
selection input
REF
Voltage reference output
NC
No connect
DQ
Serial communications
input/output
RBI
Register backup input
SB
Battery sense input
DISP
Display control input
SR
Sense resistor input
V
CC
3.0–6.5V
V
SS
Negative battery terminal
bq2011