BQ27546-G1 Datasheet, PDF (26/38 Pages) Texas Instruments – nullSingle-Cell Li-Ion Battery Fuel Gauge

bq27546-G1
SLUSC53A – MAY 2015 – REVISED DECEMBER 2015
www.ti.com
Typical Applications (continued)
10.2.1 Design Requirements
Several key parameters must be updated to align with a given application's battery characteristics. For highest
accuracy gauging, it is important to follow-up this initial configuration with a learning cycle to optimize resistance
and maximum chemical capacity (Qmax) values prior to sealing and shipping systems to the field. Successful
and accurate configuration of the fuel gauge for a target application can be used as the basis for creating a
"golden" file that can be written to all gauges, assuming identical pack design and Li-Ion cell origin (chemistry,
lot, and so on). Calibration data is included as part of this golden file to cut down on system production time. If
using this method, it is recommended to average the voltage and current measurement calibration data from a
large sample size and use these in the golden file. Table 12 shows the items that should be configured to
achieve reliable protection and accurate gauging with minimal initial configuration.
NAME
Design Capacity
Design Energy Scale
Reserve Capacity-mAh
Cycle Count Threshold
Chem ID
Load Mode
Load Select
Qmax Cell 0
Cell0 V at Chg Term
Terminate Voltage
Ra Max Delta
Charging Voltage
Taper Current
Taper Voltage
Dsg Current Threshold
Chg Current Threshold
Quit Current
Avg I Last Run
Avg P Last Run
Table 12. Key Data Flash Parameters for Configuration
DEFAULT
1000
1
0
900
0100
1
1
1000
4200
3200
44
4200
100
100
60
75
40
–299
–1131
UNIT
mAh
—
mAh
mAh
hex
—
—
mAh
mV
mV
mΩ
mV
mA
mV
mA
mA
mA
mA
mW
RECOMMENDED SETTING
Set based on the nominal pack capacity as interpreted from the cell
manufacturer's data sheet. If multiple parallel cells are used, should be set to N
× Cell Capacity.
Set to 10 to convert all power values to cWh or to 1 for mWh. Design Energy
is divided by this value.
Set to desired runtime remaining (in seconds/3600) × typical applied load
between reporting 0% SOC and reaching Terminate Voltage, if needed.
Set to 90% of configured Design Capacity.
Should be configured using TI-supplied Battery Management Studio (bqStudio)
software. Default open-circuit voltage and resistance tables are also updated in
conjunction with this step.
Do not attempt to manually update reported Device Chemistry as this does not
change all chemistry information. Always update chemistry using the bqStudio
software tool.
Set to applicable load model, 0 for constant current or 1 for constant power.
Set to load profile which most closely matches typical system load.
Set to initial configured value for Design Capacity. The gauge will update this
parameter automatically after the optimization cycle and for every regular
Qmax update thereafter.
Set to nominal cell voltage for a fully charged cell. The gauge will update this
parameter automatically each time full charge termination is detected.
Set to empty point reference of battery based on system needs. Typical is
between 3000 and 3200 mV.
Set to 15% of Cell0 R_a 4 resistance after an optimization cycle is completed.
Set based on nominal charge voltage for the battery in normal conditions
(25°C, and so on). Used as the reference point for offsetting by Taper Voltage
for full charge termination detection.
Set to the nominal taper current of the charger + taper current tolerance to
ensure that the gauge will reliably detect charge termination.
Sets the voltage window for qualifying full charge termination. Can be set
tighter to avoid or wider to ensure possibility of reporting 100% SOC in outer
JEITA temperature ranges that use derated charging voltage.
Sets threshold for gauge detecting battery discharge. Should be set lower than
minimal system load expected in the application and higher than Quit Current.
Sets the threshold for detecting battery charge. Can be set higher or lower
depending on typical trickle charge current used. Also should be set higher
than Quit Current.
Sets threshold for gauge detecting battery relaxation. Can be set higher or
lower depending on typical standby current and exhibited in the end system.
Current profile used in capacity simulations at onset of discharge or at all times
if Load Select = 0. Should be set to nominal system load. Is automatically
updated by the gauge every cycle.
Power profile used in capacity simulations at onset of discharge or at all times
if Load Select = 0. Should be set to nominal system power. Is automatically
updated by the gauge every cycle.
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