Features

ä Complete bq2050 Power Gauge solution for Li-Ion

battery packs

ä Battery information available over a single-wire

bidirectional serial port

ä Battery state-of-charge monitoring for 2- to 4-cell

series applications

ä On-board regulator allows direct connection to the

battery

ä “L” version includes push-button activated LEDs to

display state-of-charge information

ä Nominal capacity pre-configured

ä 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

hasa1

µF 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