BQ2010_15 Datasheet, PDF (13/26 Pages) Texas Instruments – Gas Gauge IC

Not Recommended For New Designs
bq2010
The bq2010 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
> 0°C
-20°C < T < 0°C
< -20°C
Available Capacity Calculation
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 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 bq2010. The
NAC registers are incremented during charge actions
and decremented during discharge and self-discharge
actions. The correction factors for charge/discharge effi-
ciency 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 bq2010 detects a valid charge, NACL resets
to 0. Writing to the NAC registers affects the available
charge counts and, therefore, affects the bq2010 gas gauge
operation. Do not write the NAC registers 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
V_CC is greater than 2V. The contents of BATID have no
effect on the operation of the bq2010. There is no de-
fault setting for this register.
Last Measured Discharge Register (LMD)
LMD is a read/write register (address=05h) that the
bq2010 uses as a measured full reference. The bq2010
adjusts LMD based on the measured discharge capacity
of the battery from full to empty. In this way the
bq2010 updates the capacity of the battery. LMD is set
to PFC during a bq2010 reset.
Secondary Status Flags Register (FLGS2)
The read-only FLGS2 register (address=06h) contains
the secondary bq2010 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
The fast charge regime efficiency factors are used when
CR = 1. When CR = 0, the trickle charge efficiency fac-
tors are used. The time to change CR varies due to the
user-selectable count rates.
The discharge rate flags, DR2–0, are bits 6–4.
FLGS2 Bits
7
6
5
4
3210
-
DR2 DR1 DR0 - - -
They are used to determine the current discharge re-
gime as follows:
DR2
0
0
DR1
0
0
DR0
0
1
V_SR (V)
V_SR > -150mV
V_SR < -150mV
The overload flag (OVLD) is asserted when a discharge
overload is detected, V_SR < -250mV. OVLD remains as-
serted as long as the condition persists and is cleared
0.5 seconds after V_SR > -250mV. The overload condition
is used to stop sampling of the battery terminal character-
istics for end-of-discharge determination. Sampling is re-
enabled 0.5 secs after the overload condition is removed.
FLGS2 Bits
7
65
4
3
2
-
--
-
-
-
1
0
- OVLD
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