Features
Complete smart battery management solution for
Li-Ion battery packs
Accurate measurement of available battery
capacity
Provides overvoltage, undervoltage, and
overcurrent protection
Designed for battery pack integration:
Small size
I n cl u d e s b q 2 0 4 0 a n d b q 2 0 5 8 I C s, a n d
configuration EEPROM
On-board charge and discharge control FETs
Low operating current for minimal battery
drain
Critical battery information available over two-wire
serial port
"L" version includes 4 push-button activated LEDs
to display state-of-charge information
General Description
The bq2148 Smaart Battery Module provides a complete
and compact battery management solution for Li-Ion bat-
tery packs. Designed for battery pack integration, the
bq2168 combines the bq2040H Gas 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, undervoltage, and overcurrent conditions. The
board works with three or four Li-Ion series cells.
The Gas 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 SMBC/SMBD. The
bq2148 uses the SMBus communications protocol and
supports the Smart Battery Data Commands in the SBD
specification. The supervisor circuit 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 bq2040 and bq2058 data
sheets for the specifics on the operation of the power
gauge and supervisor ICs.
Unitrode configures the bq2168 based on the information
requested in Table 1.
The configuration defines all the
EEPROM parameters and the protection threshold. Fig-
ure 1 shows how the module connects to the cells.
The bq2148L includes four LEDs to display remaining capac-
ity in 25% increments of the learned capacity. The LEDs are
activated with the onboard push-button switch.
A module development kit is also available for the
bq2148. The bq2148B-KT or the bq2148LB-KT includes
one configured module and the following:
1)
An EV2200-40 interface board that allows connec-
tion 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 bq2040
from any standard Windows 3.1x or 95 PC.
Pin Descriptions
POS
PACK+/Pack positive
NEG
PACK-/Pack negative
SMBC
Communications clock
SMBD
Serial data
ITEST
Overcurrent test input
B1P
Battery 1 positive input
B1N
Battery 1 negative input
B2N
Battery 2 negative input
B3N
Battery 3 negative input
B4N
Battery 4 negative input
1
Smart Battery Module with LEDs
and Pack Supervisor
Preliminary
bq2148
5/99
2
Customer Name: ______________________________________________________________________________________________
Contact: _______________________________________________________
Phone:____________________________
Address:________________________________________________________________________________________________
Sales Contact: __________________________________________________
Phone: ____________________________
Board Configuration
LEDs and switch
________________
Yes or No
Display mode
________________
Relative or Absolute
Discharge current (3.9A max.)
Min ____________
Avg ____________
Max ___________
Duration at max. discharge
________________
Overvoltage threshold (4.25, 4.30, or 4.35V) ____________________________
Number of series cells _________________
EEPROM Configuration
Typical Values
Remaining time alarm (min) _______________
Sets the low time alarm level
10 min
Remaining capacity alarm
(mAh)
_______________
Sets the low capacity alarm level
C/10
Charging voltage (mV)
_______________
Sets the requested charging voltage
4.1V/cell
Design cpaacity (mAh)
_______________
Defines the battery pack capacity
3600
Design voltage (mV)
_______________
Defines the battery pack voltage
10800
Manufacturer date
_______________
Battery pack manufacturer date
mm/dd/yy
Serial number
_______________
Battery pack serial number
0-65535
Fast-charging current (mA)
_______________
Sets the requested charging current
1C
Maintenance charging
current (mA)
_______________
Sets the requested maintenance charging
current
0
Li-Ion taper current (mA)
_______________
Sets the upper limit for charge termination
C/10
Maximum overcharge (mAh) _______________
Sets the maximum amount of overcharge
128mAh
Maximum temperature (
C) _______________ Sets the maximum charge temperature
61
C
T/t (C/min)
_______________
Sets the termination rate
4.6C/20s
Fast-charge efficiency (%)
_______________
Sets the fast-charge efficiency factor
100%
Maintenance charge effi-
ciency (%)
_______________
Sets the maintence charge efficiency factor
100%
Self-discharge rate (%/day)
_______________
Sets the batterys self-discharge rate
0.2%/day
EDV1 (mV)
_______________
Sets the initial end-of-discharge warning
3.0V/cell
EDVF (mV)
_______________
Sets the final end-of-discharge warning
2.8V/cell
Hold-off timer for
T/t (sec.) _______________
Sets the hold off period for
T/t
termination
320s
Manufacturer name
_______________
Programs manufacturer's name (11 char. max)
bq
Device name
_______________
Programs device name (7 char. max)
bq202
Chemistry
_______________
Programs pack's chemistry (5 char. max)
LION
Manufacturer data
_______________
Open field (5 char. max)
2040
FAE approval:
_______________
Date: ________________
Table 1. bq2148 Module Configuration
Preliminary
bq2148
3
FG2148-1.eps
Battery Pack
B4N
B3N B2N B1N
B1P
NEG
POS
bq2148
Load
Charger
Cells
PACK+
PACK-
Figure 1. Module Connection Diagram
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
bq2148
Preliminary
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.
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