BQ2014H_15 Datasheet, PDF (1/28 Pages) Texas Instruments – Low-Cost NiCd/NiMH Gas Gauge IC

bq2014H
Low-Cost NiCd/NiMH Gas Gauge IC
Features
➤ Accurate measurement of avail-
able capacity in NiCd or NiMH
batteries
➤ Low-cost battery management so-
lution for pack integration
- As
little
as
1
2
square
inch
of
PCB for complete circuit
- Low operating current (120µA
typical)
- Less than 100nA of data
retention current
➤ High-speed (5kb/s) single-wire
communication interface (HDQ
bus) for critical battery
parameters
➤ Communication with an external
charge controller such as the
bq2004
➤ Direct drive of remaining capacity
LEDs
➤ Automatic rate and temperature
compensation of measurements
➤ 16-pin narrow SOIC
General Description
The bq2014H NiCd/NiMH Gas
Gauge IC is intended for battery-
pack or in-system installation to
maintain an accurate record of
available battery capacity. The IC
monitors a voltage drop across a
sense resistor connected in series
between the negative battery termi-
nal and ground to determine
charge and discharge activity of
the battery. Compensations for bat-
tery temperature, self-discharge,
and rate of discharge are applied to
the charge counter to provide avail-
able capacity information across a
wide range of operating conditions.
Battery capacity is automatically re-
calibrated, or “learned,” in the
course of a discharge cycle from full
to empty.
Nominal available capacity may be
directly indicated using a five-
segment LED display. The bq2014H
also supports a simple single-line
bidirectional serial link to an exter-
nal processor (common ground). The
5kb/s HDQ bus interface reduces
communications overhead in the
external microcontroller.
Internal registers include available
capacity and energy, temperature,
voltage and current, and battery
status. The external processor may
also overwrite some of the bq2014H
gas gauge data registers.
The bq2014H can operate from the
batteries in the pack. The REF out-
put and an external transistor allow
a simple, inexpensive voltage regu-
lator to supply power to the circuit
from the cells.
Pin Connections
Pin Names
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
NC
13
HDQ
12
RBI
11
SB
10
DISP
9
SR
16-Pin Narrow SOIC
PN20140H..eps
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
Charge complete
input
V_SS
SR
DISP
SB
RBI
HDQ
NC
REF
V_CC
System ground
Sense resistor input
Display control input
Battery sense input
Register backup input
Serial communications
input/output
No connect
Voltage reference output
Supply voltage
SLUS030A–JUNE 1999 - REVISED OCTOBER 2003
1