Texas Instruments bq2012 Gas Gauge IC with Slow-Charge Control User's Manual

bq2012 Gas Gauge IC With

Slow-Charge Control means of controlling charge based

Features General Description

on the battery's charge state.

Conservative and repeatable The bq2012 Gas Gauge IC is in- Nominal available charge may be di- measurement of available charge tended for battery-pack or in-system rectly indicated using five- or six- in rechargeable batteries installation to maintain an accurate segment LED display. These seg-

record of available battery charge. ments are used to graphically indi-

Charge control output

The IC monitors voltage drop cate nominal available charge. across sense resistor connected in

Designed for battery pack inte-

The bq2012 supports simple

series between the negative battery

gration

single-line bidirectional serial link to

terminal and ground to determine

an external processor (common

charge and discharge activity of the

120µA typical standby current

ground). The bq2012 outputs battery

battery.

(self-discharge estimation mode) information in response to external

Self-discharge of Ni MH and Ni Cd commands over the serial link.

Small size enables imple- batteries is estimated based on an

mentations in as little as Internal registers include available

internal timer and temperature sen-

square inch of PCB charge, temperature, capacity, battery

sor. Compensations for battery tem-

ID, battery status, and programming

perature and rate of charge or dis-

Integrate within system or as pin settings. To support subassembly

charge are applied to the charge,

stand-alone device testing, the outputs may also be con-

discharge, and self-discharge calcu-

trolled. The external processor may

lations to provide available charge

Display capacity via single- also overwrite some of the bq2012 gas

information across wide range of

wire serial communication gauge data registers.

operating conditions. Battery capac-

port or direct drive of LEDs

ity is automatically recalibrated, or

The bq2012 may operate directly

“learned,” in the course of dis-

Measurements compensated for from three or four cells. With the

charge cycle from full to empty.

current and temperature REF output and an external transis-

tor, simple, inexpensive regulator

The bq2012 includes charge con-

Self-discharge compensation us-

can be built to provide VCC across

trol output that, when used with

ing internal temperature sensor

greater number of cells.

other full-charge safety termination

16-pin narrow SOIC methods, can provide cost-effective

Pin Connections Pin Names

LCOM LED common output REF Voltage reference output

SEG1/PROG1 LED segment 1/ CHG Charge control output

LCOM VCC

program input

SEG1/PROG1 REF DQ Serial communications

SEG2/PROG2 LED segment 2/ input/output

SEG2/PROG2 CHG

program input

SEG3/PROG3 DQ EMPTY Empty battery indicator

SEG3/PROG3 LED segment 3/ output

SEG4/PROG4 EMPTY

program input

SEG5/PROG5 SB SB Battery sense input

SEG4/PROG4 LED segment 4/

SEG6/PROG6 DISP

program input DISP Display control input

VSS SR

SEG5/PROG5 LED segment 5/ SR Sense resistor input program input

16-Pin Narrow SOIC

PN201201.eps VCC 3.0–6.5V

SEG6/PROG6 LED segment 6/ program input VSS System ground