
1
Features
Conservative and repeatable
measurement of available capac-
ity in Lithium Ion rechargeable
batteries
Designed for battery pack inte-
gration
-
120
μ
A typical operating
current
-
Small size enables imple-
mentations in as little as
12
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 bq2050 Lithium Ion Power
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 and rate of charge
or discharge are applied to the
charge, discharge, and self-discharge
calculations to provide available ca-
pacity information across a wide
range of operating conditions. Bat-
tery capacity is automatically recali-
brated, 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. These seg-
ments are used to graphically indi-
cate available capacity. The bq2050
supports a simple single-line bidi-
rectional serial link to an external
processor (common ground). The
bq2050 outputs battery information
in response to external commands
over the serial link.
The bq2050 may operate directly
from one cell (V
BAT
> 3V). With the
REF output and an external transis-
tor, a simple, inexpensive regulator
can be built for systems with more
than one series cell.
Internal registers include available
capacity, temperature, scaled avail-
able energy, 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 bq2050
power gauge data registers.
LCOM
LED common output
SEG
1
/PROG
1
LED segment 1/
program 1 input
SEG
2
/PROG
2
LED segment 2/
program 2 input
SEG
3
/PROG
3
LED segment 3/
program 3 input
SEG
4
/PROG
4
LED segment 4/
program 4 input
SEG
5
/PROG
5
LED segment 5/
program 5 input
PROG
6
Program 6 input
1
PN205001.eps
16-Pin Narrow SOIC
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
VCC
REF
N/C
DQ
RBI
SB
DISP
SR
LCOM
SEG1/PROG1
SEG2/PROG2
SEG3/PROG3
SEG4/PROG4
SEG5/PROG5
PROG6
VSS
REF
Voltage reference output
N/C
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
System ground
Pin Connections
Pin Names
bq2050
9/96 C
Lithium Ion Power Gauge IC