Datasheet

2. Programmed Full Count (PFC) or initial bat
-
tery capacity:
The initial LMD and gas gauge rate values are pro
-
grammed by using PROG
1
–PROG
4
. The bq2050H
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 bq2050H “learns” a new capacity reference.
Example: Selecting a PFC Value
Given:
Sense resistor = 0.05
Ω
Number of cells = 2
Capacity = 1000mAh, Li-Ion battery, coke-anode
Current range = 50mA to 1A
Relative display mode
Self-discharge =
NAC
512
per day @ 25°C
Voltage drop over sense resistor = 2.5mV to 50mV
Nominal discharge voltage = 3.6V
Therefore:
1000mAh
*
0.05
Ω
= 50mVh
6
bq2050H
PROG
x
Pro-
grammed
Full
Count
(PFC)
PROG
4
= L PROG
4
= Z or H
Units
12
PROG
3
= H PROG
3
= Z PROG
3
= L PROG
3
= H PROG
3
= Z PROG
3
= L
-- -
SCALE =
1/80
SCALE =
1/160
SCALE =
1/320
SCALE =
1/640
SCALE =
1/1280
SCALE =
1/2560
mVh/
count
H H 49152 614 307 154 76.8 38.4 19.2 mVh
H Z 45056 563 282 141 70.4 35.2 17.6 mVh
H L 40960 512 256 128 64.0 32.0 16.0 mVh
Z H 36864 461 230 115 57.6 28.8 14.4 mVh
Z Z 33792 422 211 106 53.0 26.4 13.2 mVh
Z L 30720 384 192 96.0 48.0 24.0 12.0 mVh
L H 27648 346 173 86.4 43.2 21.6 10.8 mVh
L Z 25600 320 160 80.0 40.0 20.0 10.0 mVh
L L 22528 282 141 70.4 35.2 17.6 8.8 mVh
V
SR
equivalent to 2
counts/s (nom.)
90 45 22.5 11.25 5.6 2.8 mV
Table 2. bq2050H Programmed Full Count mVh, V
SR
Gain Selections
Pin
Connection
PROG
5
Compensation/Self-Discharge
(See Tables 3 and 4)
DISP
Display State
H Coke anode/disabled LEDs disabled
Z Coke anode/
NAC
512
LEDs on when charging
L Graphite anode/
NAC
512
LEDs on for 4 s
Table 1. Self-Discharge and Capacity Compensation