Page 1
Features
ä
Complete and compact charge/discharge counter
ä
Combines the bq2018, voltage regulator, sense
resistor, and backup capacitor on a single PCB
ä
Communicates charge/discharge information to a
host with a single-wire interface
ä
Designed for battery pack integration
–
Less than 0.5 square inches
–
Small size allows it to fit in the crevice formed
by two adjacent cells
–
Low operating current
ä
Direct connections for the pack cells and
communications port
General Description
The bq2118 Power Minder mini-board provides a complete and compact solution for charge and discharge
counting of all types of battery chemistries, including
NiCd, NiMH, or Li-Ion batteries. Designed for battery
pack integration, the bq2118 incorporates a bq2018
Power Minder IC, supply voltage regulator, sense resistor,
and backup capacitor on a small circuit board. The module provides direct connections for the positive and negative terminals of the series cells in the battery pack, and
can fit in the crevice formed by two adjacent cells. The
bq2118 allows a battery pack to be equipped easily with
accurate charge/discharge counting electronics.
Unitrode configures the bq2118 based on the informa
tion requested in Table 1. The configuration defines the
battery chemistry, the number of series cells, and the
charge/discharge current. Figure 1 shows how the mod
ule connects to the cells.
A module development kit is also available for the
bq2118. The bq2118B-KT includes one configured module and the following:
1. An EV2200-18 interface board that allows connection to the serial port of an AT-compatible computer.
2. Menu-driven software to display charge/discharge
activity and to allow user interface to the bq2118
from any standard Windows 3.1 or 95 PC.
Pin Descriptions
BAT+
Battery positive/pack positive
BAT-
Battery negative
HDQ
Communications port
PACK-
Pack negative
WAKE
Wakeup output
RBI
Register backup input
V
CC
bq2018 supply voltage
1
Power Minder™ Mini-Board
Preliminary
bq2118
5/99
Page 2
2
bq2118
Preliminary
Customer Name: ___________________________________________________________________________
Contact: _________________________________________ Phone: ______________________________
Address: _________________________________________________________________________________
_________________________________________________________________________________
Sales Contact: ____________________________________ Phone: ______________________________
Number of series battery cells ____________________
Coke or graphite cell anode ____________________
Battery pack capacity (mAh) ____________________
Discharge rate into load (4.0A max) Min. ________ Avg. _________ Max. _________
Charge rate (4.0A max) ____________________
FAE Approval:_____________________________________ Date:________________________________
Table 1. bq2118 Module Configuration
FG2118MCD.eps
Battery Pack
BAT-
PACK-
BAT+bq2118
Load
Charger
Cells
PACK+PACK-
Figure 1. Module Connection Diagram
Page 3
3
RBI
SR2
SR1
WAKE
HDQ
VSS
VCC
REG
BQ2018
U1
1
2
3
45
6
7
8
C1
VCC
SST113
Q1
BAT+
BZX84C5V6
D1
2
HDQ
BZX84C5V6
D2
2
100
R5
C4
C2
C3
BAV99
D3
100K
d
s
R4
RBI
PACK-
BAT-
1W
0.05
R1
100K
R3
100K
R2
WAKE
1K
R6
VCC
0.01µF
0.1µF
0.1µF
0.1µF
0.1µF
C5
2018typAp.eps
bq2118 Schematic
Preliminary
bq2118
Page 4
4
bq2118 Board
bq2118
Preliminary
bq2118 B – XXX
Package Option:
B = Board-level product
Device:
Power Minder Mini-Board
Customer Code:
Blank = Sample or Pre-production
1
KT = Evaluation system
XXX = Customer-specific; assigned by Unitrode
2
Ordering Information
Notes: 1. Requires configuration sheet (see Table 1)
2. Example production part number: bq2118B-001
Page 5
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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.
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Copyright 1999, Texas Instruments Incorporated
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