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BQ40Z50-R3-DEVICE-FW: Schematic-Parts and additional questions

nils kornau
Prodigy 30 points

Part Number: BQ40Z50-R3-DEVICE-FW

Hey there,

i am working with the BQ40Z50-R3 in my current design. Out of the development work i come to several questions:

- I am planing to add the BQ2961 to my design. How can I set the precise threshold of OVP and UVP. Do I need to add extra components for this? Is there any additional components needed which i can not see in the reference

- Is there a way to protect the input Pins Vx with TVS diodes against voltage preaks?

- How many layers do you recommand for the PCB design?

- What is the difference between the AGND and the GND in the reference design? I see the place of usage but how can i separate it in my design?

- Do you recommand any specific width for tracks due to high current in the layout?

- Do you have information about the difference between R2 and R3? I can only order R2 on the "standard" distribution way.

- Do you have any recommandation due to EMC design?

Thanks for your help

  • 0
    TI__Mastermind 24870 points

    Hello Nils,

    I'm assigning this to the protectors team. For future reference, make sure to post the correct part number for your question.

  • 0
    TI__Guru* 81035 points

    Hi Nils,

    Regarding the BQ2961, the OVP and UVP are factory programmed and cannot be changed. There are different options available - see the Device Options Table 1 in the datasheet.

    I will leave the remaining questions for the BQ40Z50 for the gauge team to help you with.

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    TI__Mastermind 24870 points

    Hello Nils,

    The EMC portion will be based on the pins not exceeding abs max. That's something you will need to design for in your system.

    The gauge ground should be connected to a non-high current path ground and as close to the battery cell ground as possible.

  • 0 in reply to Matt Sunna
    Prodigy 30 points

    Hi Matt,

    thanks for your answer. The threshold is factory programmed, yes. But it is a threshold range which is given so how to use the exact point of voltage or is this random? The option tables don't cover the full range. Are there more combination available? I need OVP @ 3,6V and UVP @ 2,0V.

    Best regards,

    Nils

  • 0 in reply to Kang Kang
    Prodigy 30 points

    Hi Kang,

    thanks for your answer. What is the idea of your first sentence "pins not exceeding abs max"

    Bests,

    nils

  • 0 in reply to nils kornau
    TI__Guru* 81035 points

    Hi Nils,

    Unfortunately, the BQ2961 cannot support OVP below 3.85V. However, the BQ77904, BQ77905, BQ77915 can all support these specific settings. There is currently not an orderable part number with these specific settings, so a new device number would need to be generated. There would need to be a good business case to generate a new part number. Can you look at these devices to see if they are a good fit for you (start with the BQ77904)? I can put you in touch with our marketing folks if you think this is an option you want to go with. You will need to let them know your expected volumes.

    Thanks,

    Matt