bq2016

GAS GAUGE IC FOR

HIGH DISCHARGE RATES

SLUS475A– JANUARY 2001 – REVISED NOVEMBER 2002

8

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

functional description (continued)

Rate and

Temperature

Compensation

Charge

Current

+

Inputs

Nominal

Available

Charge

(NAC)

Rate and

Temperature

Compensation

Discharge

Current

Temperature

Compensation

Self-Discharge

Timer

–

–

≤

+

+

Last

Measured

Discharge

(LMD)

Discharge

Count

Register

(DCR)

Qualified

Transfer

Temperature

Translation

Temperature, Voltage,

Other Data

Main Counters and

Capacity Reference (LMD)

Outputs

Chip-Controlled

Available Charge

LED Display

Serial

Port

Figure 5. Operational Overview Diagram

main gas gauge registers

programmed full count (PFC)

The programmed full count (PFC) register stores the user-specified battery full capacity. The 8-bit PFC registers

stores the full capacity in mVh scaled as shown in Table 2. The VPFC input sets the PFC value and the counting

scale on a bq2016 initialization (power on reset).

nominal available capacity (NAC)

The main counter, NAC, represents the available battery capacity at any given time.

Battery charging

increments the NAC register, while battery discharging and self-discharge decrement the NAC register. The

bq2016 compensates the charge and discharge inputs to NAC for rate and temperature efficiencies.

NAC counts up during charge to a maximum value of LMD and down during discharge and self-discharge to

0. The bq2016 resets NAC to 0 on initialization and when the bq2016 sets the EDV bit on discharge. To prevent

overstatement of charge during periods of overcharge, NAC stops incrementing when NAC = LMD.