• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 188 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ75614-Q1:

Jimmy Karlsson
Prodigy 30 points
Part Number: BQ75614-Q1

Hi,

I have a question concerning how to interpret the datasheet for the VCn voltages.

I have designed a circuit that should be able to handle both 6S and 12S depending on which resistors you mount. For 6S we connect VC7 and up to the BAT-pin as described in the datasheet. This worked well and we got everything to run as expected. Then we tried to apply 12S (48V) without modifying the resistors and that killed the IC. We also did not have any cell voltages connected, just powering the VBAT-pin.

We interpreted the datasheet so that it would not be any problem to connect it this way. So my main question is if this was wrongly interpreted or if we have another problem that caused this issue.

Best Regards, Jimmy

  • 0
    TI__Expert 7000 points

    Hi Jimmy,

    Is VBAT shorting to ground? Is VC7 and up also shorting to ground without the resistors? Or is the IC acting as an open circuit? The IC should have no problem handling 48V on VBAT so identifying where the IC broke can shed light on what went wrong.

    Regards,

    David

  • 0 in reply to David Ray
    Prodigy 30 points

    Hi David, thanks for your answer.

    I'll try to bring some more context. We don't use any cell balancing so all the CBn-pins are tied to the BAT-pin, here I'm have become a little unsure if the CB0-pin needs a cap to GND or if it can be connected just to BAT as well.

    Then for the VC-pins, VC13-14 are always tied directly to BAT. Then if we want to use a 6S configuration we tie VC7 to VC12 to BAT via 0-ohms resistors. Here, we made a mistake and did not tie VC0 directly to ground, but just out to our cell voltage connector, so it will be floating if we don't connect anything to that connector. 

    So the scenario when it broke was that after we had tested it for a while with no problems using our 6S-config with VC7 to VC14 tied to BAT and running on 24V we connected 48V to this configuration without changing anything and after that we get no contact with the chip. It should be noted that there was nothing connected to the VC-pins here (except those tied to BAT), just 24V straight to BAT (via the filter). Then I repeated this on another board but slowly increased the voltage with low current limit to protect the chip but the same thing happened, but now at ~32V. 

    Hope you understand my description, I'm not sure I can post screenshots from the datasheet or from my schematic based on the datasheet?

    Do you have any idea what could be the problem? 

    Best Regards, Jimmy

  • 0 in reply to Jimmy Karlsson
    TI__Expert 7000 points

    Hi Jimmy,

    Hope you are doing well. This may be related to how the CBn pins are connected together:

    What is the voltage difference between CB1 and CB0? or CB0 and AVSS? this could be the issue. If further debugging is needed, please send the VC/CB/BAT schematic.

    Regards,

    David