Datasheet

11500
11000
EDV2
10500
EDV1
10000
9500
9000
8500
8000
7500
Voltage(mV)
10 9 8 7 6 5 4 3 2 1 0
%Capacity
45C/500mA
20C/500mA
BatteryLow%=7%,Load=500mA
11500
11000
EDV2
10500
EDV0
10000
9500
9000
8500
8000
7500
Voltage (mV)
10 9 8 7 6 5 4 3 2 1 0
% Capacity
Battery Low % = 7%, Temperature = 35 C
o
35C/2A
35C/500mA
35C/1A
7000
EDV1
EDV0,1,2 + EMF F
BL
*
Ť
I
LOAD
Ť
R0 F
TZ
F
CY
F
BL
+ f (C0, C ) C1, T)
F
TZ
+ f (R1, T0, T, C ) C1, TC)
bq2060A
www.ti.com SLUS500D –OCTOBER 2001– REVISED OCTOBER 2011
EDV Discharge Rate and Temperature Compensation
If EDV compensation is enabled, the bq2060A calculates battery voltage to determine EDV0, EDV1, and EDV2
thresholds as a function of battery capacity, temperature, and discharge load. (See Figure 11 and Figure 12.)
Figure 11. EDV Calculations vs Figure 12. EDV Calculations vs
Capacity for Various Temperatures Capacity for Various Loads
The general equation for EDV0, EDV1, and EDV2 calculation is
where
• EMF is a no-load battery voltage that is higher than the highest EDV threshold that is computed. EMF is
programmed in mV in EMF/EDV1 EE 0x74–0x75.
• I
LOAD
is the current discharge load. (9)
F
BL
is the factor that adjusts the EDV voltage for battery capacity and temperature to match the no-load
characteristics of the battery.
(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 C1/C0 Factor/EDV2 EE 0x78–79.
The Residual Capacity Factor is stored in the upper 5 bits of EE 0x78–0x79.
Residual Capacity Factor C1 = RESIDUAL% * 2.56.
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.
(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 Factor EE
0x7c–0x7d.
• T0 adjusts the variation of impedance with battery temperature. T0 is programmed in EDV T0 Factor EE
0x76–0x77.
• TC adjusts the variation of impedance for cold temperature (T < 23°C). TC is programmed in EDV TC EE
0x07.
F
CY
is the factor that adjusts for changing cell impedance as the battery pack is cycled:
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