BQ2060A_15 Datasheet, PDF (9/61 Pages) Texas Instruments – SBS v1.1-Compliant Gas Gauge IC

bq2060A
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Table 1. Example VCELL₁–VCELL₄ Divider and
Input Range
VOLTAGE
INPUT
VCELL₄
VCELL₃
VCELL₂
VCELL₁
VOLTAGE
DIVISION RATIO
16
16
8
8
FULL-SCALE
INPUT (V)
20
20
10
10
SLUS500D – OCTOBER 2001 – REVISED OCTOBER 2011
Table 2. SRC Input Range
SENSE RESISTOR
(Ω)
0.02
0.03
0.05
0.1
FULL-SCALE INPUT
(A)
± 12.5
± 8.3
±5
± 2.5
Current
The SRC input of the bq2060A measures battery charge and discharge current. The SRC ADC input converts
the current signal from the series sense resistor and stores the result in Current(). The full-scale input range to
SBC is limited to ±250 mV, as shown in Table 2.
Temperature
The TS input of the bq2060A along with an NTC thermistor measures the battery temperature as shown in
Figure 5. The bq2060A reports temperature in Temperature(). THON may be used to connect the bias source to
the thermistor when the bq2060A samples the TS input. THON is high impedance for 60 ms when the
temperature is measured, and driven low otherwise.
GAS GAUGE OPERATION
General
The operational overview in Figure 6 illustrates the gas gauge operation of the bq2060A. Table 3 and
subsequent text describes the bq2060A registers.
The bq2060A accumulates a measure of charge and discharge currents and estimates self-discharge of the
battery. The bq2060A compensates the charge current measurement for temperature and state-of-charge of the
battery. It also adjusts the self-discharge estimation based on temperature.
The main counter RemainingCapacity()(RM) represents the available capacity or energy in the battery at any
given time. The bq2060A 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 full-charge reference for relative capacity indication. The bq2060A updates FCC when 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 only tracks discharge of the battery. The
bq2060A 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 bq2060A learns the true discharge capacity of the battery under
system use conditions.
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