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BQ76930: Designed with high rating MOSFET in a circuit

Art Mecina
Genius 16655 points
Part Number: BQ76930
Other Parts Discussed in Thread: BQ78350-R1, TIDA-00449, BQ77216, TIDA-00255, BQ76200, TIDA-00792, BQ76940, TIDA-010030, BQ76920

Hello Guys,

Good day.

Our customer have a query regarding maximum current feasibility of bq76930 actually current requirements for battery pack(7s3P i.e. 28V)  BMS is 20 A continuous charging current and 60 A  continuous  discharging current also bms must support peak discharging current of 150 A for short duration i.e. 30 to 40 seconds etc.

Considering these requirements he couldn't find any BMS on TI website. There is one BQ76930 evaluation board but it doesn't fulfill his requirements for current as specified before. So real question is Can he design his own BMS with bq76930 chip with high rating mosfets in a circuit?

Thanks in advance!

Art

  • 0
    TI__Guru 54715 points

    Hi Art,

    Yes, the BQ76930 could support the current since it sees current as a voltage across the sense resistor.  Remember that the CC  will have a dynamic range and that the protection settings may further limit that range.  SCD can be set to 200 mV, also the maximum of the CC and is short, OCD can be set to 100 mV but has a maximum delay of 1.28 s.  So the system would need to pass the 150A at 100 mV setting considering tolerances with timing done by the host MCU.  This will limit the resolution of current measurement.

    With high current whether on board or remote, check for transient voltages and protect inputs if needed.  See the end of section 10 of https://www.ti.com/lit/pdf/slua749 

  • 0 in reply to WM5295
    TI__Genius 16655 points

    Hello Will,

    Thanks for looking into this!

    The customer though have follow-up inquiries:

    1) You mentioned about a host MCU. Any  MCU recommendation fit for BQ76930 ?

    2) Does texas instruments pre programmed these IC's(bq76930 and host MCU) before delivering to it's clients? 

    3) Any helping material regarding design of individuals circuits like balancing circuits, Protection circuits etc for bq76930?

    Thanks!

    Art

  • 0 in reply to Art Mecina
    TI__Guru 54715 points

    Hi Art,

    1. Certainly the MSP430 family is a low power processor with many device options to accommodate different needs in a system beyond the communication with the BQ76930.  TIDA-00449 has an implementation with the MSP430 and BQ76930.  Certainly a customer may have an MCU they prefer and can talk to the I2C from the BQ76930.  For gauging the BQ78350-R1 is available, it has well defined behaviors but does not have the flexibility of an MCU.

    2. The BQ76930 has registers and is always configured by the MCU.  TI does have the BQ78350-R1 gauge available for the BQ769x0 family, it provides CEDV gauging and protection features. The device is programmed but must have parameters loaded to configure the specific behaviors desired for the end product.

    3. There are a number of TI Designs which may be helpful.  Check the product folders for both the BQ76930 and BQ76940 since the implementations are similar other than the cell count. TIDA-00449 mentioned above uses the BQ76930 with MCU.  TIDA-00255 is the EVM board which has measurement shunt resistors, configuration options, and test points so it may not be as simple as it may first seem.  TIDA-00792 uses the BQ76940 with the BQ78350-R1 gauge and the BQ76200 high side switch to enable easy low side referenced communication.  TIDA-010030 is another design including secondary protection.  If secondary protection is an interest the BQ77216 is now sampling which will support up to 16 cells with a single package.

  • 0 in reply to WM5295
    TI__Genius 16655 points

    Hello Will,

     The customer is happy with the detailed answer. He have one last question though.

    Is there any simulation software where he can place BQ series IC and these Controllers? These simulation would help him to acquire progressive results and and order calculated items and hardware. So kindly let me know if there are any software for simulation purposes.

    I am only seeing the "bq76940/bq76930/bq76920 Evaluation Software" on the device product page. Is there anything else he can use aside from this?

    Thanks!

    Art

  • 0 in reply to Art Mecina
    TI__Guru 54715 points

    Hi Art,

    I'm not aware of any simulation software.

  • 0 in reply to WM5295
    TI__Genius 16655 points

    Thanks for the clarification Will!

    We can close this thread now.

    Best regards,

    Art