BQ2060SS Datasheet, PDF (42/59 Pages) Texas Instruments – SBS V1.1-COMPLIANT GAS GAUGE IC

bq2060
SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005
www.ti.com
EEPROM PROGRAMMING (continued)
F_BL is the factor that adjusts the EDV voltage for battery capacity and temperature to match the no-load
characteristics of the battery.
F_BL + f (C0, C ) C1, T)
(10)
where
•
C (0%, 3%, or Battery Low % for EDV0, EDV1, and EDV2, respectively) and C0 are the capacity-related EDV
adjustment factors. C0 is programmed in the lower 11 bits of EDV C0 Factor/EDV2 EE 0x78–79. The Residual
Capacity Factor is stored in the upper bits of EE 0x78–0x79.
Residual Capacity Factor C1 = RESIDUAL% x 256
RESIDUAL % is the desired battery capacity remaining at EDV0 (RM = 0).
• T is the current temperature in °K
R0 * F_TZ represents the resistance of the battery as a function of temperature and capacity.
F_TZ + f (R1, T0, T, C ) C1)
(11)
• R0 is the first order rate dependency factor stored in EDV R0 Factor EE 0x7a–0x7b.
• T is the current temperature; C is the battery capacity relating to EDV0, EDV1, and EDV2; and C1 is the
desired residual battery capacity remaining at EDV0 (RM = 0).
• R1 adjusts the variation of impedance with battery capacity. R1 is programmed in EDV R1 Rate Factor EE
0x7c–0x7d.
• T0 adjusts the variation of impedance with battery temperature. T0 is programmed in EDV T0 Rate Factor
EE 0x76–0x77.
11500
Battery Low % = 7%, Load = 500mA
11000
EDV2
10500
EDV1
10000
9500
45C/500 mA
20C/500 mA
9000
8500
8000
7500
10 9 8 7 6 5 4 3 2 1 0
% Capacity
Figure 11. EDV Calculations vs. Capacity for Various Temperatures
F_CY is the factor that adjusts for changing cell impedance as the battery pack is cycled:
where
F_CY + f (A0, Cycle Count())
(12)
• 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
42