bq2016

GAS GAUGE IC FOR

HIGH DISCHARGE RATES

SLUS475A– JANUARY 2001 – REVISED NOVEMBER 2002

11

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

programmable configuration settings (continued)

internal or external thermistor

The PROG pin programs whether the bq2016 uses an internal or external thermistor according to the following

table. It also defines the fast charge and trickle-rate detection thresholds for NAC calibration.

Table 3. PROG Selections

PROG LEVEL

LOW

NOM (VCC)

HI

T

TRICKLE RATE

FAST CHARGE

DETECTION THRESHOLD

(FCDT)

Rv (k)

Rg (k)

1

0/12

≤ 1/12 <

2/12

I

VDMF

< VSR < 2 mV

VSR > 2 mV for 30s

Open

0

2

2/12

≤ 3/12 <

4/12

I

VDMF

< CRate < C/8

CRate

> C/5 for 30s

1000

332

3

4/12

≤ 5/12 <

6/12

I

—

—

1000

715

4

6/12

≤ 7/12 <

8/12

E

VDMF

< VSR < 2 mV

> 2 mV for 30s

715

1000

5

8/12

≤ 9/12 <

10/12

E

VDMF

< CRate < C/8

CRate

> C/5 for 30s

332

1000

6

10/12

≤ 11/12 ≤

12/12

E

—

—

0

Open

NOTE: The bq2016 does not perform NAC calibration on charge with options 3 and 6. VDMF = 300

µV uncalibrated or 100 µV calibrated.

programming example

Given:

Sense resistor = 0.003

Ω

Chemistry = NiCd

Capacity = 2000 mAh

Discharge current range = 1 A to 10 A

Charge current = 200 mA to 4 A

Voltage drop over sense resistor = –30 mV to 12 mV

Internal thermistor with 2 mV FCDT

Therefore

2000 mAh

× 0.003 = 6 mVh

Select

VPFC level = 5

PROG level = 1

TS pin = grounded

The initial full battery capacity is 5.4 mVh (1800 mAh) until the bq2016 learns a new capacity with a qualified

discharge from full to EDV.

charge and discharge count counting

charge counting

The bq2016 detects charge activity when VSR = VSR2 – VSR1 is greater than the digital filter threshold. If charge

activity is detected, the bq2016 increments NAC at a rate proportional to VSR and activates the LED display

if VSR > 2 mV. Charge actions increment the NAC after compensation for charge rate and temperature. Charge

counting continues until VSR drops below VDMF.

discharge counting

The bq2016 detects discharge activity when VSR = VSR2 – VSR1 is more negative than the digital filter threshold.

If discharge activity is detected, the bq2016 decrements NAC and increments DCR at a rate proportional to

VSR and activates the LED display if VSR < –2 mV. Discharge actions decrement NAC and increment DCR after

compensation for discharge rate and temperature. Discharge counting continues until VSR rises above –VDMF.