Features
c228 Complete smart battery management solution for
Li-Ion battery packs
c228 Accurate measurement of available battery
capacity
c228 Provides overvoltage, undervoltage, and
overcurrent protection
c228 Designed for battery pack integration:
– Small size
– Includes bq2040 and bq2058 ICs, and
configuration EEPROM
– On-board charge and discharge control FETs
– Low operating current for minimal battery
drain
c228 Critical battery information available over two-wire
serial port
c228 "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
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