BQ2052_15 Datasheet, PDF(5/20 Page) Texas Instruments

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BQ2052_15 Datasheet, PDF (5/20 Pages) Texas Instruments – Gas Gauge IC

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Not Recommended For New Designs

Preliminary bq2052

PROGx

Table 2. bq2052 Programmed Full Count mVh

Programmed

Full Count

(PFC)

48128

46080

43264

39936

38400

36096

31744

28928

26112

SCALE =

1/40

1203

1152

1082

998

960

902

794

723

653

PROG3

SCALE =

1/80

602

576

541

499

480

451

397

362

327

SCALE =

1/160

301

288

271

250

240

226

199

181

164

Units

mVh/

count

mVh

Main Gas-Gauge Registers

Programmed Full Count

The PFC register stores the user-specified battery full

capacity. The 8-bit PFC registers stores the full capacity

in mVh scaled as shown in Table 2.

Full Nominal Available Capacity

The FNAC register stores the full capacity reference of

the battery. It can be programmed to initialize to PFC

or zero. The 8-bit FNAC register stores data scaled to

the same units as PFC. The bq2052 does not update

FNAC during the course of operation; therefore, if it is

programmed to 0 on initialization, it must be written to

full using the serial port.

Discharge Count Register

The DCR is the main gas gauging register and contains

the cumulative amount of discharge counted by the

bq2052. The 16-bit register stores data scaled to the

same units as PFC.

Compensated Available Capacity

The CAC registers contain the current available capac-

ity of the battery. The data stored in CAC represents

the amount of remaining capacity of the battery compen-

sated for rate and temperature use conditions. Tables 3,

4, and, 5 outline the options for typical efficiency com-

pensation factors for lithium primary batteries. The

bq2052 applies the efficiency factors to FNAC to derive

CAC.

The bq2052 applies the compensation according to the

formula:

CAC = [FCE â FNAC] - DCR

Where FCE is the calculated efficiency compensation

factor, FNAC = Full Nominal Available Capacity and

DCR = Discharge Count Register.

The bq2052 calculates an FCE based on the battery dis-

charge rate and temperature. The discharge rate por-

tion of the FCE compensation is a âpeak holdâ function;

therefore, the bq2052 latches the highest discharge rate

it has measured and uses the highest rate to calculate

FCE throughout the complete discharge cycle. The

highest discharge rate measured by the bq2052 is stored

in MRATE (address = 12h).

The bq2052 does not latch the temperature portion of an

FCE calculation. Therefore, CAC may increase or de-

crease during the course of a complete discharge cycle if

a temperature shift causes a change in the calculated

FCE value.

Programming the bq2052

The bq2052 is programmed with the PROG1â6 pins.

During power-up or initialization, the bq2052 reads the

state of these six three-level inputs and latches in the

programmable configuration settings.

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