BQ2040 Datasheet, PDF (20/33 Pages) Texas Instruments – Gas Gauge IC With SMBus Interface

bq2040
The OVLD value is:
Where OVLD is:
0 Current < programmed rate
1 Current > programmed rate
The First End-of-Discharge Voltage flag (EDV1), bit 1, is
set when Voltage < EDV1 and OVLD = 0 and cleared
when VQ = 1 and Voltage > EDV1.
FLAGS1 Bits
765432
1
0
-
-
-
-
-
- EDV1 -
The EDV1 value is:
Where EDV1 is:
0 VQ = 1 and Voltage > EDV1
1 Voltage < EDV1 and OVLD = 0
The Final End-of-Discharge Voltage flag (EDVF), bit 0, is
set when Voltage < EDVF and OVLD = 0 and cleared
when VQ = 1 and Voltage > EDVF.
FLAGS1 Bits
7654321
0
-
-
-
-
-
-
- EDVF
The EDVF value is:
Where EDVF is:
0 VQ = 1 and Voltage > EDVF
1 Voltage < EDVF and OVLD = 0
SBD Seal
The bq2040 address space can be “locked” to enforce the
SBS specified access to each command code. To lock the
address space, the bq2040 must be initialized with EE
0x3d set to b0h. Once this is done, only commands
0x00-0x04 may be written. Attempting to write to any
other address will cause a “no acknowledge” of the data.
Reading will only be permitted from the command codes
listed in the SBD specification plus the five locations
designated as optional manufacturing functions 1–5
(0x2f, 0x3c–0x3f).
Programming the bq2040
The bq2040 requires the proper programming of an ex-
ternal EEPROM for proper device operation. Each mod-
ule can be calibrated for the greatest accuracy, or gen-
eral “default” values can be used. An EV2200-40 pro-
gramming kit (interface board, software, and cable) for
an IBM-compatible PC is available from Benchmarq.
The bq2040 uses a 24LC01 or equivalent serial EE-
PROM (capable of read operation to 2.0V) for storing the
various initial values, calibration data, and string infor-
mation. Table 1 outlines the parameters and addresses
for this information. Tables 10 and 11 detail the various
register contents and show an example program value
for an 2400mAh 4-series Li-Ion battery pack, using a
50mΩ sense resistor.
Error Codes and Status Bits
Error codes and status bits are listed in Table 8 and Ta-
ble 9, respectively.
20