BQ2050_15 Datasheet, PDF (6/27 Pages) Texas Instruments – Lithium Ion Power Gauge™ IC

Not Recommended For New Designs
bq2050
2. Programmed Full Count (PFC) or initial bat-
tery capacity:
The initial LMD and gas gauge rate values are pro-
grammed by using PROG1–PROG4. The bq2050 is
configured for a given application by selecting a
PFC value from Table 2. The correct PFC may be
determined by multiplying the rated battery capac-
ity in mAh by the sense resistor value:
Battery capacity (mAh) _* sense resistor (Ω) =
PFC (mVh)
Selecting a PFC slightly less than the rated capac-
ity provides a conservative capacity reference until
the bq2050 “learns” a new capacity reference.
Example: Selecting a PFC Value
Given:
Sense resistor = 0.05Ω
Number of cells = 2
Capacity = 1000mAh, Li-Ion battery, coke-anode
Current range = 50mA to 1A
Relative display mode
Serial port only
Self-discharge
=
NAC
512
per
day
@
25°C
Voltage drop over sense resistor = 2.5mV to 50mV
Nominal discharge voltage = 3.6V
Therefore:
1000mAh _* 0.05Ω = 50mVh
Table 1. bq2050 Programming
Pin
Connection
PROG5 Compensation/
Self-Discharge
PROG6
NAC on Reset
H
Table 4/Disabled
PFC
Z
Table
4/
NAC
512
0
L
Table
3/
NAC
512
0
Note:
PROG5 and PROG6 states are independent.
DISP
Display State
LEDs disabled
LEDs on when charging
LEDs on for 4 sec.
Table 2. bq2050 Programmed Full Count mVh Selections
PROGx
12
Pro-
grammed
Full
Count
(PFC)
--
-
HH
49152
HZ
45056
HL
40960
ZH
36864
ZZ
33792
ZL
30720
LH
27648
LZ
25600
LL
22528
VSR equivalent to 2
counts/sec. (nom.)
PROG4 = L
PROG4 = Z
PROG3 = H PROG3 = Z PROG3 = L PROG3 = H PROG3 = Z PROG3 = L Units
SCALE =
1/80
SCALE = SCALE = SCALE = SCALE = SCALE = mVh/
1/160
1/320
1/640
1/1280
1/2560 count
614
307
154
76.8
38.4
19.2
mVh
563
282
141
70.4
35.2
17.6
mVh
512
256
128
64.0
32.0
16.0
mVh
461
230
115
57.6
28.8
14.4
mVh
422
211
106
53.0
26.4
13.2
mVh
384
192
96.0
48.0
24.0
12.0
mVh
346
173
86.4
43.2
21.6
10.8
mVh
320
160
80.0
40.0
20.0
10.0
mVh
282
141
70.4
35.2
17.6
8.8
mVh
90
45
22.5
11.25
5.6
2.8
mV
6