Features

ä Complete bq2012 Gas Gauge solution for NiCd or

NiMH battery packs

ä Output for slow-charge control of battery pack

ä Battery information available over a single-wire

bidirectional serial port

ä Battery state-of-charge monitoring for 4- to 12-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 and cell chemistry pre-configured

ä Compact size for battery pack integration

General Description

The bq2112 Gas Gauge Module provides a complete and

compact solution for capacity monitoring of NiCd and

NiMH battery packs. Designed for battery pack integra-

tion, the bq2112 incorporates a bq2012 Gas Gauge IC, a

current sense resistor, and all other components neces-

sary to accurately monitor and display the capacity of 3

to 12 series cells.

The bq2112L includes six surface-

mounted LEDs to display remaining capacity in 20% in-

crements of the learned capacity (relative mode) or pro-

grammed capacity (absolute mode). The sixth LED is

used in absolute mode to represent an overfull condition

(charge above the programmed capacity). The LEDs are

activated with the onboard push--button switch.

Contacts are provided on the bq2112 for direct connec-

tion to the battery stack (BAT+, BAT-), the serial com-

munications port (DQ), the empty indicator (EMPTY),

and the charge control output (CHG). Please refer to the

bq2012 data sheet for the specifics on the operation of

the Gas Gauge.

Unitrode configures the bq2112 based on the informa-

tion requested in Table 1. The configuration defines the

number of series cells, the nominal battery pack capac-

ity, the self-discharge rate, and the LED display mode.

A module development kit is also available for the

bq2112. The bq2112B-KT or bq2112LB-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 with the bq2112 to display

charge/discharge activity and to allow user inter-

face to the bq2012 from any standard DOS PC.

3)

Source code for the TSR.

Pin Descriptions

P1

DQ/Serial communication port

P2

BAT+/Battery positive/pack positive

P3

CHG/Charge control output

P4

EMPTY/Empty indicator output

P5

GND/Ground

P6

PACK-/Pack negative

P7

BAT-/Battery negative

1

bq2112

5/99 B

NiCd or NiMH Gas Gauge Module

with Slow-Charge Control