BQ2014_15 Datasheet, PDF (1/27 Pages) Texas Instruments – Gas Gauge IC with External Charge Control

Not Recommended For New Designs
bq2014
Gas Gauge IC with External Charge Control
Features
➤ Conservative and repeatable
measurement of available charge
in rechargeable batteries
➤ Charge control output operates an
external charge controller such as
the bq2004 Fast Charge IC
➤ Designed for battery pack inte-
gration
- 120µA typical standby current
➤ Display capacity via single-wire
serial communication port or di-
rect drive of LEDs
➤ Measurements compensated for
current and temperature
➤ Self-discharge compensation using
internal temperature sensor
➤ User-selectable end-of-discharge
threshold
➤ Battery voltage, nominal avail-
able charge, temperature, etc.
available over serial port
➤ 16-pin narrow SOIC
General Description
The bq2014 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 the 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, dis-
charge, and self-discharge calcula-
tions to provide available charge in-
formation across a wide range of op-
erating conditions. Battery capacity
is automatically recalibrated, or
“learned,” in the course of a dis-
charge cycle from full to empty.
The bq2014 includes a charge con-
trol output that controls an external
Fast Charge IC such as the bq2004.
Nominal Available Charge (NAC)
may be directly indicated using a
five-segment LED display.
The bq2014 supports a simple single-
line bidirectional serial link to an ex-
ternal processor (with a common
ground). The bq2014 outputs battery
information in response to external
commands over the serial link.
Internal registers include available
charge, temperature, capacity, bat-
tery voltage, battery ID, battery
status, and programming pin set-
tings. To support subassembly test-
ing, the outputs may also be con-
trolled. The external processor may
also overwrite some of the bq2014
gas gauge data registers.
The bq2014 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
DONE
7
VSS
8
16
VCC
15
REF
14
CHG
13
DQ
12
EMPTY
11
SB
10
DISP
9
SR
16-Pin Narrow SOIC
PN201401.eps
12/95 C
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
DONE
Fast charge complete
1
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