BQ2012_15 Datasheet, PDF (13/26 Pages) Texas Instruments – Gas Gauge IC With Slow-Charge Control

Not Recommended For New Designs
bq2012
The EDVF values are:
FLGS1 Bits
7 65 4
3
2
-
--
-
-
-
1
0
- EDVF
Where EDVF is:
0 Valid charge action detected, VSB ≥ 0.95V
1 VSB < 0.95V providing that OVLD=0 (see
FLGS2 register description)
Temperature and Gas Gauge Register
(TMPGG)
The read-only TMPGG register (address=02h) contains
two data fields. The first field contains the battery tem-
perature. The second field contains the available charge
from the battery.
TMPGG Temperature Bits
7
6
5
4
3210
TMP3 TMP2 TMP1 TMP0 - - -
The bq2012 contains an internal temperature sensor.
The temperature is used to set charge and discharge ef-
ficiency factors as well as to adjust the self-discharge co-
efficient.
The temperature register contents may be translated as
shown in Table 7.
The bq2012 calculates the available charge as a function
of NAC, temperature, and a full reference, either LMD
or PFC. The results of the calculation are available 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
NAC / “Full Reference”
-20°C < T < 0°C
< -20°C
0.75 _* NAC / “Full Reference”
0.5 _* NAC / “Full Reference”
Table 7. Temperature Register Translation
TMP3
0
0
0
0
0
0
0
0
1
1
1
1
1
TMP2
0
0
0
0
1
1
1
1
0
0
0
0
1
TMP1
0
0
1
1
0
0
1
1
0
0
1
1
0
TMP0
0
1
0
1
0
1
0
1
0
1
0
1
0
Temperature
T < -30°C
-30°C < T < -20°C
-20°C < T < -10°C
-10°C < T < 0°C
0°C < T < 10°C
10°C < T < 20°C
20°C < T < 30°C
30°C < T < 40°C
40°C < T < 50°C
50°C < T < 60°C
60°C < T < 70°C
70°C < T < 80°C
T > 80°C
The adjustment between > 0°C and -20°C < T < 0°C has
a 10°C hysteresis.
Nominal Available Charge Registers
(NACH/NACL)
The read/write NACH high-byte register (address=03h)
and the read-only NACL low-byte register (address=17h)
are the main gas gauging register for the bq2012. The
NAC registers are incremented during charge actions and
decremented during discharge and self-discharge actions.
The correction factors for charge/discharge efficiency are
applied automatically to NAC.
On reset, if PROG6 = Z or low, NACH and NACL are
cleared to 0; if PROG6 = high, NACH = PFC and NACL
= 0. When the bq2012 detects a valid EDV1, NACH and
NACL are reset to 0. Writing to the NAC registers affects
the available charge counts and, therefore, affects the
bq2012 gas gauge operation. Do not write the NAC regis-
ters to a value greater than LMD.
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 bq2012. There is no de-
fault setting for this register.
Last Measured Discharge Register (LMD)
LMD is a read/write register (address=05h) that the
bq2012 uses as a measured full reference. The bq2012
adjusts LMD based on the measured discharge capacity
13