bq2010
Gas Gauge IC
Features
General Description
➤ Conservative and repeatable
measurement of available charge
in rechargeable batteries
The bq2010 Gas Gauge IC is intended
for battery-pack or in-system installation to maintain an accurate record of
a battery's available 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.
➤ Designed for battery pack integration
-
120µA typical standby 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
NiMH and NiCd 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, discharge,
and self-discharge calculations to provide available charge 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.
➤ 16-pin narrow SOIC
The bq2010 may operate directly
from 3 or 4 cells. With the REF output and an external transistor, a simple, inexpensive regulator can be built
to provide V CC across a greater
number of cells.
Internal registers include available
charge, temperature, capacity, 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 bq2010
gas gauge data registers.
Nominal available charge may be
directly indicated using a five- or
six-segment LED display. These segments are used to indicate graphically the nominal available charge.
Pin Connections
The bq2010 supports a simple
single-line bidirectional serial link to
an external processor (common
ground). The bq2010 outputs battery
information in response to external
commands over the serial link.
Pin Names
➤ Accurate measurements across a
wide range of current (> 500:1)
LCOM
LCOM
1
16
VCC
SEG1/PROG1
2
15
REF
SEG2/PROG2
3
14
4
13
DQ
SEG4/PROG4
5
12
EMPTY
SEG5/PROG5
6
11
SB
SEG6/PROG6
7
10
DISP
REF
Voltage reference output
NC
No connect
DQ
Serial communications
input/output
EMPTY
Empty battery indicator
output
SB
Battery sense input
DISP
Display control input
SEG5/PROG5 LED segment 5/
program 5 input
SR
Sense resistor input
VCC
3.0–6.5V
SEG6/PROG6 LED segment 6/
program 6 input
VSS
System ground
NC
SEG3/PROG3
LED common output
SEG1/PROG1 LED segment 1/
program 1 input
VSS
8
9
SR
16-Pin Narrow SOIC
SEG2/PROG2 LED segment 2/
program 2 input
SEG3/PROG3 LED segment 3/
program 3 input
SEG4/PROG4 LED segment 4/
program 4 input
PN201001.eps
4/95 D
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