298261.6178
Capacity Gain
CC Gain
=
´
CC
CC
I
CC Gain
CC Offset
ADC
Coulomb Counter Offset Samples
=
-
Calibration
81
SLUUBD3D – September 2015 – Revised September 2018
Copyright © 2015–2018, Texas Instruments Incorporated
Manufacture Production
12.2.5.2 CC Gain/Capacity Gain Calibration
1. Apply a known current, which is the nominal discharge current of the battery and can be up to 100 A.
2. If
ManufacturerStatus()[CAL]
= 0, send 0x002D to
ManufacturerAccess()
to enable the
[CAL]
flag.
3. Send 0xF082 to
ManufacturerAccess()
to enable factory calibrated CC output on
ManufacturerData()
.
4. Poll
ManufacturerData()
until ZZ increments by 2 before reading data.
5. Using the
ManufacturerAccess()
Commands 0x001F and 0x0020, turn ON the CHG and DSG FETs.
6. Read the factory calibrated conversion readings of current from
ManufacturerData()
:
•
FCAL
CC
= GGgg of
ManufacturerData()
Is FCAL
CC
< 0x8000? If yes, use FCAL
CC
; otherwise, FCAL
CC
= –(0xFFFF – AAaa + 0x0001).
7. Average several readings for higher accuracy. Poll
ManufacturerData()
until ZZ increments to indicate
that updated values are available:
•
FCAL
CC
= [FCAL
CC
(reading n) + … + FCAL
CC
(reading 1)]/n
8. Using the
ManufacturerAccess()
Commands 0x001F and 0x0020, turn OFF the CHG and DSG. FETs
9. Read
Coulomb Counter Offset Samples
from data flash.
10. Calculate gain values:
11. Write the new
CC Gain
and
Capacity Gain
values to data flash.
12. Re-check the current reading. If the reading is not accurate, repeat the steps.
13. Send 0x002D to
ManufacturerAccess()
to clear the
[CAL]
flag if all calibration is complete.
12.2.6 Deadbands
The bq78350-R1 can be configured to ignore current and coulomb measurements below individually
programmable levels.
12.2.6.1 Current Deadband
When
Current()
measures a value less than the value programmed in
Current Deadband, Current()
will
report 0. This has no effect on the coulomb counting for the gas gauging functionality.
The value of
Current Deadband
should be selected based on the characterization of the battery
electronics design combined with the environment in which the battery will be used. If the PCB senses
noise causing a real no-current condition to report a non-zero value, then
Current Deadband
could be
adjusted accordingly.
12.2.6.2 Coulomb Counter Deadband
During normal operation, there could be noise generated in the battery electronics environment that could
cause the bq78350-R1 to accumulate incorrectly (positively or negatively). To filter out this noise, the
Coulomb Counter Deadband
setting is used. Any input below this threshold is not accumulated.
