Datasheet

bq27541-G1
www.ti.com SLUSAL6C –NOVEMBER 2011–REVISED OCTOBER 2012
Table 9. Constant-Current Model Used when Load Mode = 0
LoadSelect Value CURRENT MODEL USED
0 Average discharge current from previous cycle: There is an internal register that records the average discharge current through each
entire discharge cycle. The previous average is stored in this register.
1(default) Present average discharge current: This is the average discharge current from the beginning of this discharge cycle until present time.
2 Average current: based off the AverageCurrent( )
3 Current: based off of a low-pass-filtered version of AverageCurrent( ) (τ = 14s)
4 Design capacity / 5: C Rate based off of Design Capacity /5 or a C / 5 rate in mA.
5 Use the value specified by AtRate( )
6 Use the value in User_Rate-mA: This gives a completely user-configurable method.
If Load Mode = 1 (Constant Power) then the following options are available:
Table 10. Constant-Power Model Used When Load Mode = 1
LoadSelect Value POWER MODEL USED
0 Average discharge power from previous cycle: There is an internal register that records the average discharge power through each
entire discharge cycle. The previous average is stored in this register.
1 Present average discharge power: This is the average discharge power from the beginning of this discharge cycle until present time.
2 Average current × voltage: based off the AverageCurrent( ) and Voltage( ).
3 Current × voltage: based off of a low-pass-filtered version of AverageCurrent( ) (τ = 14s) and Voltage( )
4 Design energy / 5: C Rate based off of Design Energy /5 or a C / 5 rate in mA .
5 Use the value specified by AtRate( )
6 Use the value in User_Rate-Pwr. This gives a completely user- configurable method.
Reserve Cap-mAh
Reserve Cap-mAh determines how much actual remaining capacity exists after reaching 0
RemainingCapacity( ), before Terminate Voltage is reached when Load Mode = 0 is selected. A loaded rate
or no-load rate of compensation can be selected for Reserve Cap by setting the [RESCAP] bit in the Pack
Configuration data flash register.
Reserve Energy
Reserve Energy determines how much actual remaining capacity exists after reaching 0 RemainingCapacity( )
which is equivalent to 0 remaining power , before Terminate Voltage is reached when Load Mode = 1 is
selected. A loaded rate or no-load rate of compensation can be selected for Reserve Cap by setting [RESCAP]
bit in the Pack Configuration data flash register.
Design Energy Scale
Design Energy Scale is used to select the scale/unit of a set of data flash parameters. The value of Design
Energy Scale can be either 1 or 10 only, other values are not supported. For battery capacities larger than 6AHr,
Design Energy Scale = 10 is recommended.
Table 11. Data Flash Parameter scale/unit based on Design Energy Scale
DATA FLASH DESIGN ENERGY SCALE = 1 (default) DESIGN ENERGY SCALE = 10
Design Energy mWh cWh
Reserve Energy mWh cWh
Avg Power Last Run mW cW
User Rate-Pwr mWh cWh
T Rise No Scale Scaled by x10
Dsg Current Threshold
This register is used as a threshold by many functions in the bq27541-G1 to determine if actual discharge current
is flowing into or out of the cell. The default for this register should be sufficient for most applications. This
threshold should be set low enough to be below any normal application load current but high enough to prevent
noise or drift from affecting the measurement.
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