Features
c228 Complete bq2050 Power Gauge solution for Li-Ion
battery packs
c228 Battery information available over a single-wire
bidirectional serial port
c228 Battery state-of-charge monitoring for 2- to 4-cell
series applications
c228 On-board regulator allows direct connection to the
battery
c228 “L” version includes push-button activated LEDs to
display state-of-charge information
c228 Nominal capacity pre-configured
c228 Compact size for battery pack integration
General Description
The bq2150 Power Gauge Module provides a complete and
compact solution for capacity monitoring of Li-Ion battery
packs. Designed for battery pack integration, the bq2150
incorporates a bq2050 Gas Gauge IC, a current sense re-
sistor, and all other components necessary to accurately
monitor and display the capacity of 2 to 4 series cells.
The bq2150L includes five LEDs to display remaining ca-
pacity in 20% increments of the learned capacity. The
LEDs are activated with the onboard push-button switch.
Contacts are provided on the bq2150 for direct connec-
tion to the battery stack (BAT+, BAT-) and the serial
communications port (DQ). The RBI input provides
backup power to the bq2050 in the event that the cells
are removed or the battery is turned off. The bq2150
hasa1µF capacitor onboard connected to RBI to supply
backup power for about an hour. In battery packs that
use high-side FETs to control the charge/discharge of
the Li-Ion cells, the RBI input can be wired to a single
cell to provide prolonged data retention times. The SD
input allows an external signal (active low) to turn the
bq2050 IC off to minimize internal current consumption
of the battery pack and maximize storage life of the pack
in the system. When turned off, the bq2050 is non-
functional, and the RBI power source maintains register
information. Please refer to the bq2050 data sheet for
the specifics on the operation of the gas gauge.
Unitrode configures the bq2150 based on the informa-
tion requested in Table 1. The configuration defines the
number of series cells, the nominal battery pack capac-
ity, and the Li-Ion battery type (coke or graphite anode).
Figure 1 shows how the module connects to the cells.
A module development kit is also available for the
bq2150. The bq2150B-KT or the bq2150LB-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 to display charge/discharge
activity and to allow user interface to the bq2050
from any standard DOS PC.
3) Source code for the TSR.
Pin Descriptions
P1 DQ/Serial Communications port
P2 No connect
P3 BAT+/Battery positive/pack positive
P4 SD/Shutdown
P5 RBI/Register backup input
P6 GND/Ground
P7 PACK-/Pack negative
P8 BAT-/Battery negative
1
Li-Ion Power Gauge™ Module
bq2150
5/99 B