BQ2060SS Datasheet, PDF (51/59 Pages) Texas Instruments – SBS V1.1-COMPLIANT GAS GAUGE IC

bq2060
www.ti.com
SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005
The bq2060 uses the computed node voltages to calculate the reported voltages. It does not compute reported
cell voltages greater than the selected number of nodes. If no individual cell voltages are to be measured,
LCC1–LCC0 should be set to 00 and the top of the battery stack should be connected to a voltage divider to the
VCELL₄ input.
The bq2060 computes the reported voltages as
Voltage() = Vn4(LCC1–LCC0 = 11 or 00) – V_sr
Voltage() = Vn3(LCC1–LCC0 = 10) – V_sr
Voltage() = Vn2 (LCC1–LCC0 = 01) – V_sr
VCELL4 = Vn4- Vn3
VCELL3 = Vn3- Vn2
VCELL2 = Vn2- Vn1
VCELL1 = Vn1- V_sr
Current
The bq2060 scales Current() to mA units by the 16-bit value ADC Sense Resistor Gain in EE 0x68–0x69.
Adjusting ADC Sense Resistor Gain from its nominal value provides a method to calibrate the current readings
for variances in the ADC gain, internal voltage reference, and sense resistor value. The bq2060 calculates
Current() by
Current +
ƪ_{ADC Reading ) ADC Offset ADC Sense Resistor Gain}ƫ
16384
(31)
The nominal value for ADC Sense Resistor Gain is given by Equation 4.
VFC
To calibrate the coulomb counting measurement for VFC gain errors and sense resistor tolerance, the value of
VFC Sense Resistor Gain EE 0x6a-0x6b may be adjusted from its nominal value.
The nominal value of VFC Sense Resistor Gain is given by Equation 5.
The bq2060 VFC circuit can introduce a signal opposite in sign from that of the inherent device and circuit offset
to cancel this error. The offset calibration routine is initiated with commands to ManufacturerAccess().
The bq2060 calculates the offset with the calibration routine and stores the calibration value using the least 21
bits of VFC Offset in EE 0x5e–0x60.
The least 20 bits store the offset calibration value (OCV). The sign of the offset calibration value is positive if the
21st bit is 0.
0.6 V
OCV + _{VFC Offsets * 0}
(32)
Temperature
The bq2060 uses Temperature Offset in EE 0x61 to calibrate the Temperature() function for offset. The required
offset adjustment, TOFF (C), sets Temperature Offset according to the equation
Temperature Offset + TOFF 10
(33)
where
–12.8 ≤ TOFF ≤ 12.7
CONSTANTS AND STRING DATA
EEPROM Constants
Check/Byte 1 EE 0x00–0x01 and Check Byte 2 EE 0x7e–0x7f must be programmed to 0x3c7f and 0xa55a,
respectively.
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