BQ40Z50: The relationship among voltage(0x09), Cell 1~4 Voltage, BAT pin Voltage and PACK pin Voltage

Weiqian Yang

Part Number: BQ40Z50

Tool/software:

1.1. Is the cell voltage data from 0x3F or 0x007D?

1.2. We observed during the test that Voltage VS sum of Cell 1~4 Filtered voltage = 0mV, but Voltage VS sum of Cell 1~4 voltage = -3mV

2. Under the effective static condition, how large of a voltage difference between the BAT pin and the PACK pin Voltage is considered normal?

3. What is the voltage accuracy of the BAT pin and the PACK pin?

1 month ago

0 Weiqian Yang 1 month ago

Prodigy 70 points

Hello TI Team, pls help to confirm above question, tks.

0 Alan Frias 1 month ago in reply to Weiqian Yang

TI__Mastermind 27405 points

In Hello,

Your question has been assigned and will be reviewed when possible. In the meantime can you attached the .log and .gg files associated with this project.

Thank you,
Alan

0 Weiqian Yang 1 month ago in reply to Alan Frias

Prodigy 70 points

Could you just tell me what the specifications are first?

0 Miguel Castro Gonzalez 1 month ago in reply to Weiqian Yang

TI__Intellectual 1562 points

Hello Weiqian,

Please see my answers:

0x3f
1. I am not sure what the difference is between the two. I tried asking my colleagues, but they didn't know right of their head. It might be a value used by the IT.
Ideally, the difference between PACK+ and BAT+ should be 0V assuming the FETs are on. However, the FETs have Rdson value to it which add resistanc to the path. The resistance of the traces on the PCB will also matter. The resistance of the battery connections will also add up. In short, the difference between the two shouldn't be more than 100mV.
The accuracy of the BAT and PACK is measured by the ADC on the HW of the gauge which should be within 1mV.

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BQ40Z50: The relationship among voltage(0x09), Cell 1~4 Voltage, BAT pin Voltage and PACK pin Voltage