Datasheet

24
bq2040
Description
EEPROM
Address
EEPROM
Hex
Contents
Example
Values Notes
Low
Byte
High
Byte
Low
Byte
High
Byte
Reserved 0x2f 00 0 Not currently used by the bq2040.
Li-Ion taper
current
0x38 0x39 10 ff 240mA
Sets the upper taper limit for Li-Ion charge termina
-
tion. Stored in 2’s complement.
Maximum
overcharge
limit
0x3a 0x3b 9c ff 100mAh
Sets the maximum amount of overcharge before a
maximum overcharge charge suspend occurs.
Stored in 2’s complement.
Reserved 0x3c 00 0 Must be programmed to 0.
Access protect 0x3d b0 SBD access only
If the bq2040 is reset and bit 3 of this location is 0, the
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.
FLAGS1 0x3e 00 0 Initializes FLAGS1
FLAGS2 0x3f b0
Relative display
Li-Ion chemistry
bq2040 charge
control
Initializes FLAGS2.
Current
measurement
gain
1
0x46 0x47 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.
Battery voltage
offset
1
0x48 fe -2mV
Used to adjust the battery voltage offset according to
the following:
Voltage = (V
SB
(mV) + V
OFF
) ∗ Voltage gain
Temperature
offset
1
0x49 8a
13.8°C
The default value (zero adjustment) for the offset is
12.8°C or 0x80.
TOFF
NEW
= TOFF
CURRENT
+
(TEMP
ACTUAL
- TEMP
REPORTED
)∗ 10
Maximum
temperature
and ∆T step
0x4a 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).
Charge
efficiency
0x4b ff
Maintenance
compensation =
100%
Fast compensa
-
tion = 100%
Sets the fast-charge (high) and maintenance charge
(low) efficiencies. The upper nibbles sets the low effi
-
ciency and the lower nibble adjusts the high effi
-
ciency according to the equation:
Nibble = (efficiency% ∗ 256 - 196)/4
Full-charge
percentage
0x4c 9c
100%
This packed field is the two’s complement of the de
-
sired value in RM when the bq2040 determines a
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.
Table 10. Example Register Contents (Continued)