BQ2060A_15 Datasheet, PDF (44/61 Pages) Texas Instruments – SBS v1.1-Compliant Gas Gauge IC

bq2060A
SLUS500D – OCTOBER 2001 – REVISED OCTOBER 2011
www.ti.com
F_CY + f (A0, Cycle Count())
(12)
where A0 is the EDV aging factor that is stored in EDV A0 Factor EE 0x06. It should be set to 0 for most
applications.
Typical values for the EDV compensation factors for a Li-ion 3s3p 18650 pack are
• EMF = 11550
• T0 = 4475
• C0 = 235
• C1 = 0
• R0 = 5350
• R1 = 250
• A0 = 0
• TC = 3
The graphs in Figures 7, 8, and 9 show the calculated EDV0, EDV1, and EDV2 thresholds versus capacity using
the typical compensation values for different temperatures and loads for a Li-ion 3s3p 18650 pack. The
compensation values vary widely for different cell types and manufacturers and must be matched exactly to the
unique characteristics for optimal performance.
Overload Current Threshold
The Overload Current threshold is a 16-bit value stored in EE 0x46–0x47 in mA units.
Midrange Capacity Corrections
Three voltage-based thresholds, VOC25 EE 0x6c–0x6d, VOC50 EE 0x6e–0x6f, and VOC75 EE 0x70–0x71, are
used to test the accuracy of the RM-based on open-circuit pack voltages. These thresholds are stored in the
EEPROM in 2s complement of voltage in mV. The values represent the open-circuit battery voltage at which the
battery capacity should correspond to the associated state of charge for each threshold.
Self-Discharge Rate
The nominal self-discharge rate, %PERDAY (% per day), is programmed in an 8-bit value Self-Discharge Rate
EE 0x53 by the following relation:
Self -Discharge Rate = 256
-
æ 52.73 ö
çè _%PERDAY ÷ø
(13)
If programmed to 0, then self-discharge accumulation is disabled.
Light-Load Current
The amount of light-load current in mA, ILEAK, used for compensation is stored in Light Discharge Current in EE
0x2b as follows:
ILEAK ´1024
Light-Discharge Current =
45
(14)
ILEAK is between 0.044 and 11.2 mA.
Charge Efficiency
The bq2060A uses four charge-efficiency factors to compensate for charge acceptance. These factors are coded
in Charge Efficiency (EFF%), Efficiency Reduction Rate (ERR%), Efficiency Drop Off Percentage (EDOP%), and
Efficiency Temperature Compensation (TEFF%).
The bq2060A applies the efficiency factor, EFF%, when RelativeStateOfCharge() is less than the value coded in
Efficiency Drop Off Percentage EE 0x64. When RelativeStateOfCharge() is greater than or equal to the value
coded in Efficiency Drop Off Percentage, EFF% and ERR% determine the charge efficiency rate. ERR% defines
the percent efficiency reduction per percentage point of RelativeStateOfCharge() over Efficiency Drop Off
Percentage. EFF% is encoded in Charge Efficiency EE 0x4d according to the following equation:
44
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