Features
Complete and compact lithium ion gas gauge and
protection solution for three or four series cells
Accurate measurement of available battery
capacity
Provides overvoltage, undervoltage, and
overcurrent protection
Designed for battery pack integration
Small size
Includes bq2050H and bq2058 ICs
On-board charge and discharge control FETs
Low operating current for minimal battery drain
High side FET control
Battery capacity available through single-wire
serial port
"L" version includes 5 push-button activated LEDs
to display state-of-charge information
General Description
The bq2168 Power Gauge Module provides a complete and
compact battery management solution for Li-Ion battery
packs. Designed for battery pack integration, the bq2168
combines the bq2050H Power Gauge IC with the bq2058
Supervisor IC on a small printed circuit board. The board
includes all the necessary components to accurately monitor
battery capacity and protect the cells from overvoltage, un-
dervoltage, and overcurrent conditions. The board works
with three or four Li-Ion series cells.
The Power Gauge IC uses the on-board sense resistor to
track charge and discharge activity of the battery pack.
Critical battery information can be accessed through the
serial communications port at HDQ. The supervisor cir-
cuit consists of the bq2058 and two FETs. The bq2058
controls the FETs to protect the batteries during
charge/discharge cycles and short circuit conditions. The
bq2168 provides contacts for the positive and negative
terminals of each battery in the stack. Please refer to
the bq2050H and bq2058 data sheets for the specifics on
the operation of the power gauge and supervisor ICs.
Unitrode configures the bq2168 based on the informa-
tion requested in Table 1. The configuration defines the
number of series cells, the nominal battery pack capac-
ity, the self-discharge rate, the Li-Ion battery type (coke
or graphite anode), and the threshold limits. Figure 1
shows how the module connects to the cells.
The bq2168L includes five LEDs to display remaining capac-
ity in 20% increments of the learned capacity. The LEDs are
activated with the onboard push-button switch.
A module development kit is also available for the
bq2168. The bq2168B-KT or the bq2168LB-KT includes
one configured module and the following:
1)
An EV2200-50H interface board that allows con-
nection to the serial port of any AT-compatible com-
puter.
2)
Menu driven software to display charge/discharge
activity and to allow user interface to the bq2050H
from any standard Windows 3.1x or 95 PC.
Pin Descriptions
POS
Pack positive
B1P
BAT
1P
/Battery 1 positive input
B1N
BAT
1N
/Battery 1 negative input
B2N
BAT
2N
/Battery 2 negative input
B3N
BAT
3N
/Battery 3 negative input
B4N
BAT
4N
/Battery 4 negative input
ITEST
Overcurrent test input
HDQ
Serial communications port
NEG
Pack negative
1
bq2168
5/99 B
Li-Ion Power GaugeTM Module
with Pack Supervisor
2
bq2168
FG2168-1.eps
Battery Pack
B4N
B3N B2N B1N
B1P
NEG
POS
bq2168
Load
Charger
Cells
PACK+
PACK-
Figure 1. Module Connection Diagram
Customer Name: ___________________________________________________________________________
Contact: _________________________________________
Phone: ______________________________
Address: _________________________________________________________________________________
_________________________________________________________________________________
Sales Contact: ____________________________________
Phone: ______________________________
Number of series cells (3 or 4)
_____________
Coke or graphite cell anode
_____________
Battery pack capacity (mAh)
_____________
Discharge current into load (3.9A max.)
min. ________ avg. _________ max. _________
Charge current (3.9A max)
_____________
Self-discharge compensation (Y/N)
_____________
Overvoltage threshold (4.25, 4.30, or 4.35V)
_____________
LEDs and switch (Y/N)
_____________
FAE approval: ____________________________________
Date: _______________________________
Table 1. bq2168 Module Configuration
3
bq2168
FG2158cc.eps
B1P
NC
Load
or
Charger
Three-Cell Configuration
POS
NEG
B1N
B2N
B3N
B4N
B1P
Load
or
Charger
Four-Cell Configuration
POS
NEG
B1N
B2N
B3N
B4N
Note: B1P, B4N, POS, and NEG accomodate a #20 AWG stranded wire.
B1N, B2N, and B3N accomodate a #24 AWG stranded wire.
Figure 1. Module Connection Diagram
4
Component values depend on user-provided information in Table 1.
2168La.eps
1
2
3
4
bq2168 Schematic
bq2168
5
2168Lb
bq2168 Schematic (Continued)
bq2168
6
bq2168
bq2168 Board
7
Absolute Maximum Ratings
Symbol
Parameter
Value
Unit
Conditions
V
OP
Supply voltage (B1P to B4N)
18
V
DC
V
TR
Maximum transient voltage (B1P to B4N)
32
V
Maximum duration =
1.5
s
V
CHG
Charging voltage (POS to NEG)
18
V
I
CHG
Continuous charge/discharge current
3.9
A
V
OP
> 6V
T
A
= 25
C
T
OPR
Operating temperature
0 to +70
C
T
STG
Storage temperature
-55 to +125
C
Note:
Permanent device damage may occur if Absolute Maximum Ratings are exceeded. Functional operation
should be limited to the Recommended DC Operating Conditions detailed in this data sheet. Exposure to con-
ditions beyond the operational limits for extended periods of time may affect device reliability.
DC Electrical Characteristics
(T
A
= T
OPR
)
Symbol
Parameter
Minimum
Typical
Maximum
Unit
Conditions/Notes
V
OP
Operating voltage, B1P to
B4N
4.0
-
18
V
I
CCA
Operating current
-
-
350
A
R
ON
On resistance, B1P to POS
-
-
50
m
T
A
= 25
C
V
OP
= 10V
bq2168
8
DC Thresholds
(T
A
= T
OPR
)
Symbol
Parameter
Value
Tolerance
Unit
Notes
V
OV
Overvoltage threshold
4.25
50mV
V
V
CE
Charge enable voltage
V
OV
- 100mV
50mV
V
V
UV
Undervoltage limit
2.25
100mV
V
I
OC
Overcurrent limit
3.4
A
T
A
= 25
C
3.8
A
T
A
= 60
C
t
UVD
Undervoltage delay
950
50%
ms
T
A
= 30C
V
CD
Charge detect threshold
70
-60, +80
mV
t
OVD
Overvoltage delay
950
50%
ms
T
A
= 30C
t
OCD
Overcurrent delay
12
60%
ms
T
A
= 30C
Note:
The thresholds above reflect the operation of a bq2158 using the standard bq2058 IC (V
OV
= 4.25V).
Specify other versions of the bq2058 by indicating the appropriate V
OV
threshold in Table 1.
bq2168
LED Option:
L = LEDs plus switch
Blank = No LEDs or switch
Notes:
1.
Requires configuration sheet (Table 1)
2.
Example production part number: bq2168LB-001
Ordering Information
bq2168
B --
Customer Code:
Blank = Sample or Pre-production
1
KT = Evaluation system
XXX = Customer-specific; assigned by Unitrode
2
Package Option:
B = Board-level product
Device:
Li-Ion Power Gauge Module with Pack Supervisor
Change No.
Page No.
Description
Nature of Change
1
All
From Preliminary to Final
Note:
Change 1 = May 1999 B changes from Apr. 1999.
Data Sheet Revision History
IMPORTANT NOTICE
Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue
any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those
pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI's standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF
DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE ("CRITICAL
APPLICATIONS"). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR
WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER
CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO
BE FULLY AT THE CUSTOMER'S RISK.
In order to minimize risks associated with the customer's applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other
intellectual property right of TI covering or relating to any combination, machine, or process in which such
semiconductor products or services might be or are used. TI's publication of information regarding any third
party's products or services does not constitute TI's approval, warranty or endorsement thereof.
Copyright
1999, Texas Instruments Incorporated
PDF 
ZIP