BQ2052_15 Datasheet, PDF (6/20 Pages) Texas Instruments – Gas Gauge IC

Not Recommended For New Designs
bq2052 Preliminary
Programmable Configuration Settings
Design Capacity
The battery’s rated design capacity or Programmed Full
Count (PFC) is programmed with the PROG₁–PROG₃
pins as shown in Table 2, and represents the battery’s
full reference.
The correct PFC may be determined by multiplying the
rated battery capacity in mAh by the sense resistor
value:
Battery capacity (mAh) _* sense resistor (Ω) = PFC
(mVh)
Selecting a PFC slightly less than the rated capacity
provides a conservative capacity reference. The bq2052
stores the selected PFC in the PFC register (address =
10h).
Discharge Rate and Temperature Compensation
The discharge rate and temperature compensations are se-
lected using the PROG₄ pin. The level of PROG₄ on
power-up or initialization determines which compensation
table the bq2052 uses for the discharge cycle. The following
tables illustrate the calculated efficiency compensation fac-
tors at selected discharge rates and temperatures.
Table 3. Discharge Efficiency Factor Table
PROG4 = Z
Discharge Rage
TEMP 0 C/80 C/25 C/10 C/5 C/3
-20 97
99
96
92
85
81
-10 98
98
97
94
89
85
0
98
98
97
94
90
87
21
99
99
98
96
92
89
55
99
99
98
96
93
90
70
99
99
98
96
93
90
Table 4. Discharge Efficiency Factor Table
PROG4 = L
Discharge Rage
TEMP 0 C/80 C/25 C/10 C/5 C/3
-20 87
85
80
70
53
50
-10 93
91
88
80
68
51
0
96
94
91
85
74
60
21
99
97
95
89
81
68
55 100 99
97
92
85
74
70 101 100 98
93
86
76
Table 5. Discharge Efficiency Factor Table
PROG4 = H
Discharge Rage
TEMP 0 C/80 C/25 C/10 C/5 C/3
-20 92
93
92
88
83
75
-10 98
98
97
93
89
81
0
100 100 99
96
91
84
21 104 104 102 99
95
88
55 106 106 105 100 97
90
70 107 107 105 101 98
91
Display Mode
The display mode is selected using the PROG₅ pin. The
three options include a two, four, or five segment display
mode as described in Tables 7, 8, and 9.
Initial Capacity Setting
The PFC value is copied to the FNAC register if PROG6
is programmed high, otherwise FNAC defaults to 0.
FNAC may be written to the desired full capacity to ini-
tialize the pack manually.
Programming Example
Given:
Sense resistor = 0.05mΩ
Number of cells = 5 in series
Capacity = 7000mAh,
Chemistry = LiSO2
Discharge current range = 250mA to 2A
Voltage drop over sense resistor = 12.5mV to 100mV
Display mode = 5 segment bar graph display
Therefore:
7000mAh _* 0.05 = 350mVh
Select:
PFC = 26112 counts or 327mVh
PROG₁ = low
PROG₂ = low
PROG₃ = float
PROG₄ = float, high, or low depending on desired com-
pensation factors
PROG₅ = float selects five segment display
PROG₆ = high sets FNAC to PFC
With these selections, the full battery capacity is
327mVh (6540mAh).
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