Hi,
I am using the BQ76952 for my BMS design and i am trying the calibrate the board offset. But I'm having problems.
I used the calibration document and it says the following:
Board Offset Calibration Steps
1. Disable Sleep Mode (Subcommand 0x009A) to ensure voltage counts update quickly after applying a
voltage.
2. Apply a known current ICAL of 0 mA and ensure no current is flowing through the sense resistor connected
between the SRP and SRN pins.
3. After 100ms, read CC2 Counts using the READ_CAL1 subcommand 0xF081. While the CC2 Counts reading
is four bytes, only the middle two bytes need to be read (16-bit value). For best accuracy, take multiple
readings and calculate the average.
4. Read the Coulomb Counter Offset Samples settings at RAM location 0x91C6. This parameter is defined as
the number of counts of offset error that would accumulate over this many coulomb counter conversions. The
default value is 64.
5. Calculate the Board Offset:
Board Offset = Coulomb Counter Offset Samples x (CC2 Counts)
6. Write the new Board Offset value to RAM.
• Enter CONFIG_UPDATE mode (Subcommand 0x0090).
• Write Board Offset to 0x91C8.
• Exit CONFIG_UPDATE mode (Subcommand 0x0092).
7. Re-check the CC2 Counts reading. If the reading is not close to zero, repeat steps 1-5.
But i can't get the CC2 counts reading close to zero it stays around 310(average).
I also used the EVM module to calibrate the board offset with the EVM program but this also doesn't make the CC2 count zero (Also around average 300 on the EVM).
Does anybody have an solution?
