BQ2083-V1P2 Datasheet, PDF (13/55 Pages) Texas Instruments – SBS-COMPLIANT GAS GAUGE IC FOR USE WITH THE bp29311

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bq2083-V1P2
SLUS573 − JULY 2003
Self-Discharge
The bq2083−V1P2 estimates the self-discharge of the battery to maintain an accurate measure of the battery
capacity during periods of inactivity. The bq2083−V1P2 makes self-discharge adjustments to RM( ) every 1/4
seconds when awake and periodically when in sleep mode. The period is determined by Sleep Timer DF 0xe7.
The self-discharge estimation rate for 25°C is doubled for each 10 degrees above 25°C or halved for each 10 degrees
below 25°C. The following table shows the relation of the self-discharge estimation at a given temperature to the rate
programmed for 25°C (Y% per day programmed in DF 0x2c).
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Table 4. Self-Discharge for Rate Programmed
TEMPERATURE
(°C)
Temp < 10
10 ≤ Temp <20
20 ≤ Temp <30
30 ≤ Temp <40
40 ≤ Temp <50
50 ≤ Temp <60
60 ≤ Temp <70
70≤ Temp
SELF-DISCHARGE RATE
1/4 Y% per day
1/2 Y% per day
Y% per day
2Y% per day
4Y% per day
8Y% per day
16Y% per day
32Y% per day
CAPACITY
vs
TIME
1000
800
600
400
200
0
0
TA = 15°C
TA = 25°C
TA = 35°C
TA = 45°C
10
20
30
40
50
60
70
Time − Days
Figure 4. Self-Discharge at 2.5%/Day at 25°C
Figure 4 illustrates how the self-discharge estimate algorithm adjusts RemainingCapacity( ) versus temperature.
Battery Electronic Load Compensation
The bq2083−V1P2 can be configured to compensate for a constant load (as from battery electronics) present in the
battery pack at all times. The bq2083−V1P2 applies the compensation continuously when the charge or discharge
is below the digital filter. The bq2083−V1P2 applies the compensation in addition to self-discharge. The
compensation occurs at a rate determined by the value stored in Electronics Load DF 0x2d. The compensation range
is 0 µA–765 µA in steps of approximately 3 µA.
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