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BQ769142: BQ769142 hardware connection and I2C software issue

Sherman Xin
Prodigy 350 points
Part Number: BQ769142

HI Team,

Nice to talk with you! My customer has two questions about BQ769142.

1.When the circuit connection as above:
The sampling result is that the first 9 strings have correct values. However, the 10th string is on the VC16 and the VC16 sample is 1V larger, and the total voltage is also 1V larger.
When configured Vcell mode to 0x3ff, I found that under-voltage protection was reported, but actually there was no under-voltage.
When configured Vcell mode to 0x81ff, the overvoltage on VC16 was not reported.
Thus, how should Vcell mode be configured under this connection method?

2.The demo on the official website adds a 2ms delay when I2C communication as below. This delay is too long for the actual project. So, do we have to add a delay? What will happen if the delay time not be added? And can this time be adjusted to a smaller value? 

Many thanks!

BRs, Sherman

  • 0
    TI__Guru* 77343 points

    Hi Sherman,

    How many cells are connected in this system? Both of the register settings you mentioned would be for 10 cells - is this correct? Your picture shows 13 cells?

    You need to set the register for each of the VC pins that is connected to a cell, so based on your picture it should be 0x8FFF.

    For subcommands that use 0x3E, we recommend waiting 2ms, otherwise it is possible that the data read from 0x40 will not be ready. Table 9-2 of the TRM shows the average execution time for different subcommands. The other option is to poll from 0x3E to see when the command has successfully executed (as described in the BQ769x2 Software Development Guide).

    Best regards,

    Matt