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1.1.11 Fuel Gauge Operating Modes
Entry and exit of each mode is controlled by data flash parameters in the Current Thresholds subclass. The
[DSG] flag referenced below is from the MAC GaugingStatus() subcommand and is set in both RELAXATION
and DISCHARGE modes. The [DSG] flag in BatteryStatus() is slightly different—it sets only in DISCHARGE
mode and not in RELAXATION mode.
CHARGE mode is exited and RELAXATION mode is entered when Current() goes below Quit Current
for a period of Chg Relax Time. DISCHARGE mode is entered when Current() goes below
(–)Dsg Current Threshold. DISCHARGE mode is exited and RELAXATION mode is entered when Current()
goes above (–)Quit Current threshold for a period of Dsg Relax Time. CHARGE mode is entered when
Current() goes above Chg Current Threshold.
[DSG]
1
Current
Relaxation Mode
Quit Current
(–)Quit Current
1.1.12 Qmax
Qmax is used for initial capacity (RM and RSOC) estimates in conjunction with the cell voltages and
programmed chemistry information when the device resets. The Qmax Pack value should be taken from the cell
manufacturers' data sheet multiplied by the number of parallel cells. This is also used for the DesignCapacity()
function and the Design Capacity mAh data flash value.
1.1.13 CEDV Smoothing
The BQ27220 device has the ability to smooth the RemainingCapacity() during discharge in order to avoid a
drop in RelativeStateOfCharge() when the EDV thresholds are reached. This feature is enabled by setting the
Smoothing Config [SMEN] = 1 and configuring the Smoothing Start Voltage and Smoothing Delta Voltage.
The smoothing will activate only when all of the following conditions are true:
•
Current() < 0
•
Voltage() < Smoothing Start Voltage
SLUUBD4A – APRIL 2016 – REVISED NOVEMBER 2022
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1
Charge Mode
Relaxation Mode
Discharge Mode
Chg Relax Time
Figure 1-3. Fuel Gauge Operating Mode Example
Copyright © 2022 Texas Instruments Incorporated
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1
Charge Mode
Discharge Mode
General Description
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Relaxation Mode
Time
Dsg Relax Time
BQ27220
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