BQ2040_15 Datasheet, PDF (24/36 Pages) Texas Instruments – Gas Gauge IC With SMBus Interface

Not Recommended For New Designs
bq2040
Table 10. Example Register Contents (Continued)
Description
Reserved
Li-Ion taper
current
Maximum
overcharge
limit
Reserved
EEPROM
Address
Low High
Byte Byte
0x2f
0x38 0x39
0x3a 0x3b
0x3c
Access protect 0x3d
FLAGS1
0x3e
FLAGS2
0x3f
Current
measurement
gain¹
0x46 0x47
Battery voltage
offset¹
0x48
Temperature
offset¹
0x49
Maximum
temperature
and ∆T step
0x4a
Charge
efficiency
0x4b
Full-charge
percentage
0x4c
EEPROM
Hex
Contents
Low High
Byte Byte
Example
Values
Notes
00
0
Not currently used by the bq2040.
10 ff
240mA
Sets the upper taper limit for Li-Ion charge termina-
tion. Stored in 2’s complement.
9c ff
100mAh
Sets the maximum amount of overcharge before a
maximum overcharge charge suspend occurs.
Stored in 2’s complement.
00
0
Must be programmed to 0.
If the bq2040 is reset and bit 3 of this location is 0, the
b0
SBD access only
bq2040 locks access to any command outside of the SBS
data set. Program to 0xb8 for full R/W access, 0xb0 for
SBD access only.
00
0
Initializes FLAGS1
Relative display
b0
Li-Ion chemistry
bq2040 charge
Initializes FLAGS2.
control
00 0f
3840
The current gain measurement and current integra-
tion gain are related and defined for the bq2040 cur-
rent measurement. This word equals 192/sense re-
sistor value in ohms.
Used to adjust the battery voltage offset according to
fe
-2mV
the following:
Voltage = (VSB(mV) + VOFF) ∗ Voltage gain
The default value (zero adjustment) for the offset is
8a
13.8°C
12.8°C or 0x80.
TOFFNEW = TOFFCURRENT +
(TEMPACTUAL - TEMPREPORTED)∗ 10
5f
Maximum
temperature =
61.0°C
∆T step = 4.6°C
Maximum charge temperature is 69- (mt ∗ 1.6)°C (mt
= upper nibble). The ∆T step is (dT ∗ 2 + 16)/10°C
(dT = lower nibble).
Maintenance Sets the fast-charge (high) and maintenance charge
compensation = (low) efficiencies. The upper nibbles sets the low effi-
ff
100%
ciency and the lower nibble adjusts the high effi-
Fast compensa- ciency according to the equation:
tion = 100% Nibble = (efficiency% ∗ 256 - 196)/4
This packed field is the two’s complement of the de-
sired value in RM when the bq2040 determines a
9c
100%
full-charge termination. If RM is below this value,
RM is set to this value. If RM is above this value,
then RM is not adjusted.
Note:
1. Can be adjusted to calibrate the battery pack.
24