Features
Complete bq2012 Gas Gauge solution for NiCd or
NiMH battery packs
Output for slow-charge control of battery pack
Battery information available over a single-wire
bidirectional serial port
Battery state-of-charge monitoring for 4- to 12-cell
series applications
On-board regulator allows direct connection to the
battery
"L" version includes push-button activated LEDs to
display state-of-charge information
Nominal capacity and cell chemistry pre-configured
Compact size for battery pack integration
General Description
The bq2112 Gas Gauge Module provides a complete and
compact solution for capacity monitoring of NiCd and
NiMH battery packs. Designed for battery pack integra-
tion, the bq2112 incorporates a bq2012 Gas Gauge IC, a
current sense resistor, and all other components neces-
sary to accurately monitor and display the capacity of 3
to 12 series cells.
The bq2112L includes six surface-
mounted LEDs to display remaining capacity in 20% in-
crements of the learned capacity (relative mode) or pro-
grammed capacity (absolute mode). The sixth LED is
used in absolute mode to represent an overfull condition
(charge above the programmed capacity). The LEDs are
activated with the onboard push--button switch.
Contacts are provided on the bq2112 for direct connec-
tion to the battery stack (BAT+, BAT-), the serial com-
munications port (DQ), the empty indicator (EMPTY),
and the charge control output (CHG). Please refer to the
bq2012 data sheet for the specifics on the operation of
the Gas Gauge.
Unitrode configures the bq2112 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, and the LED display mode.
A module development kit is also available for the
bq2112. The bq2112B-KT or bq2112LB-KT includes one
configured module and the following:
1)
An interface board that allows connection to the se-
rial port of an AT-compatible computer.
2)
Menu-driven software with the bq2112 to display
charge/discharge activity and to allow user inter-
face to the bq2012 from any standard DOS PC.
3)
Source code for the TSR.
Pin Descriptions
P1
DQ/Serial communication port
P2
BAT+/Battery positive/pack positive
P3
CHG/Charge control output
P4
EMPTY/Empty indicator output
P5
GND/Ground
P6
PACK-/Pack negative
P7
BAT-/Battery negative
1
bq2112
5/99 B
NiCd or NiMH Gas Gauge Module
with Slow-Charge Control
2
bq2112
Customer Name: ___________________________________________________________________________
Contact: _________________________________________
Phone: ______________________________
Address: _________________________________________________________________________________
_________________________________________________________________________________
Sales Contact: ____________________________________
Phone: ______________________________
Number of series battery cells (4-12)
________________________________________
Battery type (NiCd or NiMH)
________________________________________
Battery pack capacity (mAh)
________________________________________
Discharge rate into load (3.0A max.)
Min.
Avg.
Max.
Charge rate (3.0A max)
________________________________________
Display mode (absolute or relative)
________________________________________
LEDs and switch (Y/N)
________________________________________
FAE approval: _____________________________________
Date:________________________________
Table 1. bq2112 Module Configuration
FG-961
Charger
Load
P7
P6
P2
bq2112
Cells
Battery Pack
PACK+
PACK-
Figure 1. Module Connection Diagram
4
bq2112
bq2112 Board
5
bq2112
Absolute Maximum Ratings
Symbol
Parameter
Minimum
Maximum
Unit
Conditions
V
CC
Relative to V
SS
-0.3
+7.0
V
bq2012
All other pins
Relative to V
SS
-0.3
+7.0
V
bq2012
P
SR
Continuous sense resis-
tor power dissipation
-
3
W
Thru-hole sense resistor
-
1
W
Surface mount sense resistor
I
CHG
Continuous charge/
discharge current
-
3.0
A
T
OPR
Operating temperature
0
+70
C
Commercial
T
STR
Storage temperature
-40
+85
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
(TA = TOPR)
Symbol
Parameter
Minimum
Typical
Maximum
Unit
Conditions/Notes
NumCell
Number of series cells in bat-
tery pack
4
-
12
-
BAT+
Positive terminal of pack
GND
NumCell
1.2V
*
NumCell
1.8V
*
V
BAT-
Negative terminal of pack
GND -
0.3
-
GND+2.0
V
I
CC
Supply current at BAT+ ter-
minal (no external loads)
-
200
300
A
R
DQ
Internal pull-down
500k
-
-
1
I
OL
Open-drain sink current DQ,
EMPTY, CHG
-
-
5.0
mA
1
V
OL
Open-drain output low,
DQ, EMPTY, CHG
-
-
0.5
V
1
I
OL
< 5mA
V
IHDQ
DQ input high
2.5
-
-
V
1
V
ILDQ
DQ input low
-
-
0.8
V
1
V
OS
Voltage offset
-
-
150
V
1
Note:
1. Characterized on PCB, IC 100% tested.
6
LED Option:
L = LEDs plus switch
Blank = No LEDs or switch
bq2112
DC Voltage Thresholds
(TA = TOPR)
Symbol
Parameter
Minimum
Typical
Maximum
Unit
Notes
V
EDVF
Final empty warning
0.93
0.95
0.97
V
BAT+/NumCell
1
V
EDV1
First empty warning
1.03
1.05
1.07
V
BAT+/NumCell
1
V
MCV
Maximum single-cell voltage
2.20
2.25
2.30
V
BAT+/NumCell
1
V
SRO
Sense resistor range
-300
-
+2000
mV
V
SR
+ V
OS2
V
SRQ
Valid charge
375
-
-
V
V
SR
+ V
OS 2, 3
V
SRD
Valid discharge
-
-
-300
V
V
SR
+ V
OS 2, 3
Notes:
1.
At SB input of bq2012.
2.
At SR input of bq2012.
3.
Default value; value set in DMF register.
Ordering Information
Notes:
1.
Requires configuration sheet (see Table 1)
2.
Example production part number: bq2112LB-002
bq2112
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:
NiCd or NiMH Gas Gauge Module with Slow-Charge Control
Change No.
Page No.
Description
1
2
Updated Table 1 to include 3.0A limit
1
5
Added 3.0A maximum continuous charge/discharge current specification
Note:
Change 1 = May 1999 B changes from Nov. 1997.
Data Sheet Revision History
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