Current Calibration; Temperature Calibration - Texas Instruments BQ769142 Manual

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appropriate calibration coefficients to realize a COV threshold at or close to the applied voltage level. When this
search is completed, the resulting calibration coefficient is returned by the subcommand and automatically
written into the Protections:COV:COV Threshold Override configuration parameter. If this parameter is
nonzero, the device does not use its factory trim settings, but instead uses this value.
The CUV threshold is calibrated similarly; an external voltage is applied between VC14 and VC13A equal to the
desired CUV threshold. Next, while in CONFIG_UPDATE mode, the CAL_CUV() subcommand is sent by the
host, which causes the BQ769142 device to perform a search for the appropriate calibration coefficients to
realize a CUV threshold at or close to the applied voltage level. When this search is completed, the resulting
calibration coefficient is returned by the subcommand and automatically written into the Protections:CUV:CUV
Threshold Override configuration parameter.

10.10 Current Calibration

The BQ769142 device coulomb counter ADC measures the differential voltage between the SRP and SRN pins
to calculate the system current. The device includes the optional capability for the customer to calibrate the
coulomb counter offset and current gain on the production line.
The Calibration:Current Offset:CC Offset configuration register contains an offset value in units of 32-bit
coulomb counter ADC counts / Calibration:Current Offset:Coulomb Counter Offset Samples. The value of
Calibration:Current Offset:CC Offset / Calibration:Current Offset:Coulomb Counter Offset Samples is
subtracted from the raw coulomb counter ADC counts, then the result is multiplied by Calibration:Current:CC
Gain and scaled to provide the final result in units of userA.
The BQ769142 device uses the Calibration:Current:CC Gain and Calibration:Current:Capacity Gain
configuration values to convert from the ADC value to current. The CC Gain reflects the value of the sense
resistor used in the system, while the Capacity Gain is simply the CC Gain multiplied by 298261.6178.
Both the CC Gain and Capacity Gain are encoded using a 32-bit IEEE-754 floating point format. The effective
value of the sense resistor is given by:
CC Gain = 7.4768 / (Rsense in mΩ)

10.11 Temperature Calibration

The BQ769142 device enables the customer to calibrate the internal as well as external temperature
measurements on the production line, by storing an offset value which is added to the calculated measurement
before reporting. A separate offset for each temperature measurement can be stored in the configuration
registers shown below.
Section
Calibration
Calibration
Calibration
Calibration
Calibration
Calibration
Calibration
Calibration
Calibration
Calibration
Copyright © 2021 Texas Instruments Incorporated
Table 10-1. Temperature Calibration Settings
Subsection Register Description
Temperature Internal Temp Offset
Temperature CFETOFF Temp Offset
Temperature DFETOFF Temp Offset
Temperature ALERT Temp Offset
Temperature TS1 Temp Offset
Temperature TS2 Temp Offset
Temperature TS3 Temp Offset
Temperature HDQ Temp Offset
Temperature DCHG Temp Offset
Temperature DDSG Temp Offset
Product Folder Links:
SLUSE91A – SEPTEMBER 2020 – REVISED FEBRUARY 2021
Comment
CFETOFF pin thermistor
DFETOFF pin thermistor
ALERT pin thermistor
TS1 pin thermistor
TS2 pin thermistor
TS3 pin thermistor
HDQ pin thermistor
DCHG pin thermistor
DDSG pin thermistor
BQ769142
BQ769142
Units
0.1 K
0.1 K
0.1 K
0.1 K
0.1 K
0.1 K
0.1 K
0.1 K
0.1 K
0.1 K
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