BQ2012_15 Datasheet, PDF (6/26 Pages) Texas Instruments – Gas Gauge IC With Slow-Charge Control

Not Recommended For New Designs
bq2012
Example: Selecting a PFC Value
Given:
Sense resistor = 0.1Ω
Number of cells = 6
Capacity = 2200mAh, NiCd battery
Current range = 50mA to 2A
Absolute display mode
Serial port only
Self-discharge = ^C64
Voltage drop over sense resistor = 5mV to 200mV
Therefore:
2200mAh _* 0.1Ω = 220mVh
Select:
PFC = 33792 counts or 211mVh
PROG1 = float
PROG2 = float
PROG3 = float
PROG4 = low
PROG5 = float
PROG6 = float
The initial full battery capacity is 211mVh
(2110mAh) until the bq2012 “learns” a new capac-
ity with a qualified discharge from full to EDV1.
Table 1. bq2012 Programming
Pin
Connection
H
PROG5
Self-Discharge Rate
Self-discharge disabled
PROG6
Display Mode
NAC = PFC on reset
Z
NAC
64
Absolute
L
Note:
NAC
47
Relative
PROG5 and PROG6 states are independent.
DISP
Display State
LED disabled
LED enabled on discharge when
VSRO < -4mV or during a valid charge
LED on
Table 2. bq2012 Programmed Full Count mVh Selections
PROGx
12
Programmed
Full
Count
(PFC)
PROG3 = H
--
-
Scale =
1/80
HH
49152
614
HZ
45056
563
HL
40960
512
ZH
36864
461
ZZ
33792
422
ZL
30720
384
LH
27648
346
LZ
25600
320
LL
22528
282
VSR is equivalent to 2
counts/sec. (nom.)
90
PROG4 = L
PROG4 = Z
PROG3 = Z PROG3 = L PROG3 = H PROG3 = Z PROG3 = L
Scale =
1/160
Scale =
1/320
Scale =
1/640
Scale =
1/1280
Scale =
1/2560
307
154
76.8
38.4
19.2
282
141
70.4
35.2
17.6
256
128
64.0
32.0
16.0
230
115
57.6
28.8
14.4
211
106
53.0
26.4
13.2
192
96.0
48.0
24.0
12.0
173
86.4
43.2
21.6
10.8
160
80.0
40.0
20.0
10.0
141
70.4
35.2
17.6
8.8
45
22.5
11.25
5.56
2.8
Units
mVh/
count
mVh
mVh
mVh
mVh
mVh
mVh
mVh
mVh
mVh
mV
6