Features
c228 Complete and compact charge/discharge counter
c228 Combines the bq2018, voltage regulator, sense
resistor, and backup capacitor on a single PCB
c228 Communicates charge/discharge information to a
host with a single-wire interface
c228 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
c228 Direct connections for the pack cells and
communications port
General Description
The bq2118 Power Minder mini-board provides a com-
plete 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 mod-
ule provides direct connections for the positive and nega-
tive 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 mod-
ule and the following:
1. An EV2200-18 interface board that allows connec-
tion to the serial port of an AT-compatible com-
puter.
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
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