BQ2063_15 Datasheet, PDF (8/60 Pages) Texas Instruments – SBS v1.1-COMPLIANT Li-ION GAS-GAUGE IC

bq2063
Not Recommended For New Designs
SBS v1.1ĆCOMPLIANT LiĆION GASĆGAUGE IC
WITH PROTECTOR INTERFACE
SLUS468E− MAY 2001 − REVISED APRIL 2002
general (continued)
The bq2063 accumulates a measure of charge and discharge currents and estimates self-discharge of the
battery. The bq2063 compensates the charge current measurement for temperature and state-of-charge of the
battery. The bq2063 also adjusts the self-discharge estimation based on temperature.
The main charge counter RemainingCapacity( ) (RM) represents the available capacity or energy in the battery
at any given time. The bq2063 adjusts RM for charge, self-discharge, and leakage compensation factors. The
information in the RM register is accessible through the communications ports and is also represented through
the LED display.
The FullChargeCapacity( ) (FCC) register represents the last measured full discharge of the battery. It is used
as the battery’s full-charge reference for relative capacity indication. The bq2063 updates FCC after the battery
undergoes a qualified discharge from nearly full to a low battery level. FCC is accessible through the serial
communications ports.
The Discharge Count Register (DCR) is a non-accessible register that tracks discharge of the battery. The
bq2063 uses the DCR register to update the FCC register if the battery undergoes a qualified discharge from
nearly full to a low battery level. In this way, the bq2063 learns the true discharge capacity of the battery under
system use conditions.
main gas-gauge registers
The gas-gauge register functions are described in Table 2.
RemainingCapacity( ) (RM)
RM represents the remaining capacity in the battery. The bq2063 computes RM in either mAh or 10 mWh
depending on the selected mode.
RM counts up during charge to a maximum value of FCC and down during discharge and self-discharge to 0.
In addition to charge and self-discharge compensation, the bq2063 calibrates RM at three low-battery-voltage
thresholds, EDV2, EDV1, and EDV0 and three programmable midrange thresholds VOC25, VOC50, and
VOC75. This provides a voltage-based calibration to the RM counter.
DesignCapacity( ) (DC)
The DC is the user-specified battery full capacity. It is calculated from Pack Capacity EE 0x3a-0x3b and is
represented in mAh or 10 mWh. It also represents the full-battery reference for the absolute display mode.
FullChargeCapacity( ) (FCC)
FCC is the last measured discharge capacity of the battery. It is represented in either mAh or 10 mWh,
depending on the selected mode. On initialization, the bq2063 sets FCC to the value stored in Last Measured
Discharge EE 0x38-0x39. During subsequent discharges, the bq2063 updates FCC with the last measured
discharge capacity of the battery. The last measured discharge of the battery is based on the value in the DCR
register after a qualified discharge occurs. Once updated, the bq2063 writes the new FCC value to EEPROM
in mAh to Last Measured Discharge. FCC represents the full battery reference for the relative display mode and
relative state of charge calculations.
discharge count register (DCR)
The DCR register counts up during discharge, independent of RM. DCR can continue to count even after RM
has counted down to 0. Before RM = 0, discharge activity, light discharge estimation, battery load estimation,
and self-discharge increment DCR. After RM = 0, the bq2063 does not apply self-discharge and DCR
increments only because of discharge activity, light discharge estimation, and battery load estimation. The
bq2063 initializes DCR, at the beginning of a discharge, to FCC − RM when RM is within twice the programmed
value in Near Full EE 0x55. The DCR initial value of FCC − RM is reduced by FCC/128 if SC = 0 (bit 2 in Control
Mode) and is not reduced if SC = 1. DCR stops counting when the battery voltage reaches the EDV2 threshold
on discharge.
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