BQ2011K_11 Datasheet, PDF (12/22 Pages) Texas Instruments – Gas Gauge IC for High Discharge Rates

bq2011K
Table 6. Temperature Register Contents
TMP3 TMP2 TMP1 TMP0 Temperature
0
0
0
0
T < -30°C
0
0
0
1 -30°C < T < -20°C
0
0
1
0 -20°C < T < -10°C
0
0
1
1
-10°C < T < 0°C
0
1
0
0
0°C < T < 10°C
0
1
0
1
10°C < T < 20°C
0
1
1
0
20°C < T < 30°C
0
1
1
1
30°C < T < 40°C
1
0
0
0
40°C < T < 50°C
1
0
0
1
50°C < T < 60°C
1
0
1
0
60°C < T < 70°C
1
0
1
1
70°C < T < 80°C
1
1
0
0
T > 80°C
The bq2011K calculates the available charge as a func-
tion of NAC, temperature, and a full reference, either
LMD or PFC. The results of the calculation are avail-
able via the display port or the gas gauge field of the
TMPGG register. The register is used to give available
capacity in ¹¹⁶ increments from 0 to ¹⁵¹⁶.
TMPGG Gas Gauge Bits
7 65 4
3
2
1
0
-
-
-
- GG3 GG2 GG1 GG0
The gas gauge display and the gas gauge portion of the
TMPGG register are adjusted for cold temperature de-
pendencies. A piece-wise correction is performed as fol-
lows:
Temperature
Available Capacity Calculation
> 0°C
-20°C < T < 0°C
< -20°C
NAC / “Full Reference”
0.75 _* NAC / “Full Reference”
0.5 _* NAC / “Full Reference”
The adjustment between > 0°C and -20°C < T < 0°C has
a 4°C hysteresis.
Nominal Available Charge Register (NAC)
The read/write NACH register (address=03h) and the
read-only NACL register (address=17h) are the main
gas gauging registers for the bq2011K. The NAC regis-
ters are incremented during charge actions and decre-
mented during discharge and self-discharge actions.
The correction factors for charge/discharge efficiency are
applied automatically to NAC.
If SEG4 = 0 on reset, then NACH = PFC and NACL = 0.
If SEG4 = Z or H, the NACH and NACL registers are
cleared to zero. NACL stops counting when NACH
reaches zero. When the bq2011K detects a valid charge,
NACL resets to zero; writing to the NAC register affects
the available charge counts and, therefore, affects the
bq2011K gas gauge operation.
Battery Identification Register (BATID)
The read/write BATID register (address=04h) is avail-
able for use by the system to determine the type of bat-
tery pack. The BATID contents are retained as long as
VCC is greater than 2V. The contents of BATID have no
effect on the operation of the bq2011K. There is no de-
fault setting for this register.
Last Measured Discharge Register (LMD)
LMD is a read/write register (address=05h) that the
bq2011K uses as a measured full reference. The
bq2011K adjusts LMD based on the measured discharge
capacity of the battery from full to empty. In this way
the bq2011K updates the capacity of the battery. LMD
is set to PFC during a bq2011K reset.
Secondary Status Flags Register (FLGS2)
The read-only FLGS2 register (address=06h) contains
the secondary bq2011K flags.
The charge rate flag (CR) is used to denote the fast
charge regime. Fast charge is assumed whenever a
charge action is initiated. The CR flag remains asserted
if the charge rate does not fall below 2 counts/sec.
The CR values are:
FLGS2 Bits
7
65
4
3
2
1
0
CR - -
-
-
-
-
-
Where CR is:
0 When charge rate falls below 2 counts/sec
1 When charge rate is above 2 counts/sec
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