Introduction
63
SLUUBD3D – September 2015 – Revised September 2018
Copyright © 2015–2018, Texas Instruments Incorporated
CEDV Gas Gauging
Class
Subclass
Name
Format
Size in
Bytes
Min
Max
Default
Unit
Fuel
Gauging
CEDV Cfg
Battery Low
%
Unsigned
Integer
2
0
65535
700
0.01%
Fuel
Gauging
State
Learned Full
Charge
Capacity
Integer
2
0
32767
4400
mAh
Battery Low %
should be set to match a capacity value that corresponds to the first or highest voltage
point, EDV2. It should be chosen where the capacity sensitivity to voltage is easily detectable. It is a non-
measured portion of the overall
Learned Full Charge Capacity
. If the target
Battery Low %
is changed
in the design, ensure that the initial value of
DOD at EDV2
is also adjusted accordingly.
9.1.6 Qualified Discharge
A qualified discharge occurs if the battery discharges from RC
≥
FCC –
Near Full
to the EDV2 voltage
threshold with the following conditions:
•
No valid charge activity occurs during the discharge period. A valid charge is defined as a charge of 10
mAh into the battery.
•
No more than 256 mAh of self-discharge or battery load estimation occurs during the discharge period.
•
The temperature does not drop below the low temperature thresholds programmed in
Low Temp
during the discharge period.
•
The battery voltage reaches the EDV2 threshold during the discharge period and the voltage is greater
than or equal to the EDV2 threshold minus 256 mV when the bq78350-R1 detected EDV2.
–
When
CEDV Gauging Configuration [VFLT_EN]
is set, a filter is added to the EDV detection that
is set by
CEDV Min Delta V
to improve false triggering under pulsed load activity. If the latest
compensated EDV2 voltage changes by more than CEDV Min Delta V from the previously
calculated value, then the previous one is not updated.
•
–
Current()
remains <
Overload Current
when EDV2 is reached.
•
No overload condition exists when EDV2 threshold is reached, or if RC has dropped to
Battery Low %
× FCC.
Class
Subclass
Name
Format
Size in
Bytes
Min
Max
Default
Unit
Fuel
Gauging
CEDV Cfg
Near Full
Integer
2
0
65535
200
mAh or 10
mWh
Fuel
Gauging
CEDV Cfg
Learning
Low Temp
Integer
2
–100
255
119
0.1°C
Fuel
Gauging
CEDV Cfg
Min Delta V
Filter
Integer
2
0
32767
10
mV
The bq78350-R1 sets [VDQ] = 1 in
GaugingStatus()
when a qualified discharge begins. The bq78350-R1
sets
[VDQ]
= 0 if any disqualifying condition occurs. One complication may arise regarding the state of
[VDQ] if
[CSYNC]
is set in
CEDV Gauging Configuration
. When
[CSYNC]
is enabled, RC is written to
equal FCC on valid primary charge termination. This capacity synchronization is done even if the condition
RC
≥
FCC –
Near Full
is NOT satisfied at charge termination.
FCC cannot be reduced by more than
FCC Learn Down
or increased by more than
FCC Learn Up
during
any single update cycle. The bq78350-R1 saves the new FCC value to the data flash within 4 s of being
updated.
Class
Subclass
Name
Format
Size in
Bytes
Min
Max
Default
Unit
Fuel
Gauging
CEDV Cfg
FCC Learn
Down
Integer
2
0
65535
256
mAh or 10
mWh
Fuel
Gauging
CEDV Cfg
FCC Learn
Up
Integer
2
0
65535
512
mAh or 10
mWh
