BQ2016 Datasheet, PDF (12/21 Pages) Texas Instruments – GAS GAUGE IC FOR HIGH DISCHARGE RATES

bq2016
GAS GAUGE IC FOR
HIGH DISCHARGE RATES
SLUS475A– JANUARY 2001 – REVISED NOVEMBER 2002
charge and discharge count counting (continued)
self-discharge estimation
The bq2016 continuously decrements NAC and increments DCR for self-discharge based on time and
temperature. The self-discharge count rate is programmed to be a nominal 1/80  NAC rate per day for NiCd
and a nominal 1/60 × NAC for NiMH. This is the rate for a battery whose temperature is between 20°C–30°C.
The self-discharge rate doubles every 10°C increase in temperature.
count compensations
The bq2016 compensates charge and discharge counting for temperature and rate before updating the NAC
and/or DCR. The bq2016 compensates self-discharge estimation for temperature before updating the NAC or
DCR.
charge compensations
The bq2016 compensates for charge efficiencies at a quick-charge and fast-charge rate at two different
temperature thresholds. The bq2016 applies the NiCd or NiMH factors based on the VPFC setting. For charge
compensation, quick charge is defined as a C/5 charge rate or less and fast charge is defined as a rate greater
than C/5.
The charge-compensation factors are shown in Tables 4 and 5.
charge compensations
Table 4. Charge Compensation for NiCd
CHARGE TEMPERATURE
<40C
≥ 40
QUICK CHARGE
( ≤ C / 5 ) COMPENSATION
0.80
0.75
FAST CHARGE
( > C / 5 ) COMPENSATION
0.95
0.90
Table 5. Charge Compensation for NiMH
CHARGE TEMPERATURE
<40C
≥ 40
QUICK CHARGE
( ≤ C / 5 ) COMPENSATION
0.80
0.75
FAST CHARGE
( > C / 5 ) COMPENSATION
0.90
0.85
discharge compensation
The bq2016 corrects for the rate of discharge by adjusting an internal discharge-compensation factor. The
discharge factor is based on the calculated discharge rate determined from the V_SR potential and the PFC
setting. The table below shows the compensation factors for NiCd and NiMH during discharge:
DISCHARGE RATE
DISCHARGE EFFICIENCY
( FDE ) (%)
≤1C
100
>3C
100
>6C
95
>9C
95
>12C
90
NOTE: The C Rate determination is made from LMD.
12
• POST OFFICE BOX 655303 DALLAS, TEXAS 75265