BQ2012_15 Datasheet, PDF (1/26 Pages) Texas Instruments – Gas Gauge IC With Slow-Charge Control

Not Recommended For New Designs
bq2012
Gas Gauge IC With
Slow-Charge Control
Features
➤ Conservative and repeatable
measurement of available charge
in rechargeable batteries
➤ Charge control output
➤ Designed for battery pack inte-
gration
- 120µA typical standby current
(self-discharge estimation mode)
- Small size enables imple-
mentations
in
as
little
as
1
2
square inch of PCB
➤ Integrate within a system or as a
stand-alone device
- Display capacity via single-
wire serial communication
port or direct drive of LEDs
➤ Measurements compensated for
current and temperature
➤ Self-discharge compensation us-
ing internal temperature sensor
➤ 16-pin narrow SOIC
General Description
The bq2012 Gas Gauge IC is in-
tended for battery-pack or in-system
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.
Self-discharge of NiMH and NiCd
batteries is estimated based on an
internal timer and temperature sen-
sor. Compensations for battery tem-
perature and rate of charge or dis-
charge are applied to the charge,
discharge, and self-discharge calcu-
lations to provide available charge
information across a wide range of
operating conditions. Battery capac-
ity is automatically recalibrated, or
“learned,” in the course of a dis-
charge cycle from full to empty.
The bq2012 includes a charge con-
trol output that, when used with
other full-charge safety termination
methods, can provide a cost-effective
means of controlling charge based
on the battery's charge state.
Nominal available charge may be di-
rectly indicated using a five- or six-
segment LED display. These seg-
ments are used to graphically indi-
cate nominal available charge.
The bq2012 supports a simple
single-line bidirectional serial link to
an external processor (common
ground). The bq2012 outputs battery
information in response to external
commands over the serial link.
Internal registers include available
charge, temperature, capacity, battery
ID, battery status, and programming
pin settings. To support subassembly
testing, the outputs may also be con-
trolled. The external processor may
also overwrite some of the bq2012 gas
gauge data registers.
The bq2012 may operate directly
from three or four cells. With the
REF output and an external transis-
tor, a simple, inexpensive regulator
can be built to provide VCC across a
greater number of cells.
Pin Connections
LCOM
1
SEG1/PROG1
2
SEG2/PROG2
3
SEG3/PROG3
4
SEG4/PROG4
5
SEG5/PROG5
6
SEG6/PROG6
7
VSS
8
16
VCC
15
REF
14
CHG
13
DQ
12
EMPTY
11
SB
10
DISP
9
SR
16-Pin Narrow SOIC
PN201201.eps
9/96 B
Pin Names
LCOM
LED common output
SEG₁/PROG₁ LED segment 1/
program 1 input
SEG₂/PROG₂ LED segment 2/
program 2 input
SEG₃/PROG₃ LED segment 3/
program 3 input
SEG₄/PROG₄ LED segment 4/
program 4 input
SEG₅/PROG₅ LED segment 5/
program 5 input
SEG₆/PROG₆ LED segment 6/
program 6 input
REF
CHG
DQ
EMPTY
SB
DISP
SR
V_CC
V_SS
Voltage reference output
Charge control output
Serial communications
input/output
Empty battery indicator
output
Battery sense input
Display control input
Sense resistor input
3.0–6.5V
System ground
1