Datasheet

25
bq2040
Description
EEPROM
Address
EEPROM
Hex
Contents
Example
Values Notes
Low
Byte
High
Byte
Low
Byte
High
Byte
Digital filter 0x4d 96 0.30mV
Used to set the digital magnitude filter as described in
Table 2.
Current integra
-
tion gain
1
0x4e 40 0 3.2/0.05
Represents the following: 3.2/sense resistor in ohms.
It is used by the bq2040 to scale the measured voltage
values on the SR pin in mA and mAh. This register
also compensates for variations in the reported sense
resistor value.
Self-discharge rate 0x4f 2d 0.25%
This packed field is the two’s complement of (52.73/x)
where x is the desired self-discharge rate per day (%)
at room temperature.
Voltage gain
1
0x56 0x57 17 07 7.09
Voltage gain is packed as two units. For example, (R4
+ R5)/R4 = 7.09 would be stored as: whole number
stored in 0x57 as 7 and the decimal component stored
in 0x56 as 256 x 0.09 = 23(= 17h).
Reserved 0x58 0x59 00 00 0 Should be programmed to 0.
EDVF charging
current
0x5a 0x5b 64 00 100mA Contains the desired charge current below EDVF.
End of discharge
voltage 1
0x5c 0x5d 20 d1 12000mV
The value programmed is the two’s complement of the
threshold voltage in mV.
End-of-discharge
voltage final
0x5e 0x5f 40 d4 11200mV
The value programmed is the two’s complement of the
threshold voltage in mV.
Full charge
capacity
0x60 0x61 d0 07 2000mA This value sets the initial estimated pack capacity.
∆t step
0x62 0f 20s
The ∆t step for ∆T/∆t termination equals
320 - (byte value ∗ 20).
Hold-off time 0x63 00 320s hold-off
The hold-off time is 320 - (byte value ∗ 20).
EEPROM check 2 0x64 b5 181 Must be equal to 0xb5.
Reserved 0x65 0x7f NA Not currently used by the bq2040.
Note: 1. Can be adjusted to calibrate the battery pack.
Table 10. Example Register Contents (Continued)