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Original question:

BQ78350-R1A: Connection between microcontroller and high-side FET driver

BQ76200: BMS using BQ79656-Q1

Criton Kallkkaran
Prodigy 105 points
Part Number: BQ76200
Other Parts Discussed in Thread: BQ79656-Q1, BQ79758-Q1, , BQ76952, BQ76940

Tool/software:

Hi,

I am trying to design a BMS with active cell balancing. TI team suggested  BQ79656-Q1 (16S, 4th gen, does not require NDA for evaluation) or BQ79758-Q1 (18S, 5th gen, requires NDA for evaluation). After going through the data sheet it seemed little confusing on how to connect the charge and discharge MOSFETS using BQ79656-Q1. Is it possible to integrate BQ76200 high FET driver with  BQ79656-Q1 and a microcontroller? If not how would I connect charge and discharge MOSFETS in the design that uses BQ79656-Q1?

I look forward to hearing from you.

Many thanks and Kind regards,
Criton

  • 0
    TI__Mastermind 42060 points

    Hello Criton,

    You would have to control the BQ76200 FET driver by using MCU GPIO's with MCU logic. The BQ79656-Q1 does not have pins to control FET drivers.

    Now, does your application require Q1 qualifications? If not, you could also look at the BQ76952, which is a non-stackable 16s monitor and protector, with integrated high-side FET drivers that can be used to control high-side N-Channel FETs. Additionally it has current sense and coulomb counting.

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Prodigy 105 points

    Hi Luis,

    Many thanks for getting back to me.

    Does that mean the FET driver should be controlled using the microcontroller with the data received from the BQ79656-Q1? Sounds like developing a lot of algorithms for controlling the FET driver.

    My only concern in using BQ76952 is on active cell balancing. Does it support active cell balancing?

    I look forward to hearing from you.

    Kind regards,
    Criton  

  • 0 in reply to Criton Kallkkaran
    TI__Mastermind 42060 points

    Hello Criton,

    Criton Kallkkaran said:
    Does that mean the FET driver should be controlled using the microcontroller with the data received from the BQ79656-Q1? Sounds like developing a lot of algorithms for controlling the FET driver.

    Correct. You would have to develop the algorithms to make this work correctly. The BQ76952 has this algorithm implemented and is able to efficiently control the external MOSFETs.

    Criton Kallkkaran said:
    My only concern in using BQ76952 is on active cell balancing. Does it support active cell balancing?

    Neither the BQ79656-Q1 nor the BQ76952 have active cell balancing, there is no single-chip solution that implements cell balancing.

    Both of these devices are able to perform passive cell balancing.

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Prodigy 105 points

    Hi Luis,

    Many thanks for your response.  Does BQ76952/ BQ79656-Q1 support external circuitry for active cell balancing? 

    Kind regards,
    Criton

  • 0 in reply to Criton Kallkkaran
    Prodigy 105 points

    Also to add, I could only find BQ76940 battery monitor that does not fall under One-Time Programmable memory. Did I miss any Battery monitors that have reprogrammable memory? Also does BQ76940 support external circuits for active cell balancing? If so could you please share some reference designs?

    I look forward to hearing from you.

    Many thanks and Kind regards,
    Criton

  • 0 in reply to Criton Kallkkaran
    TI__Mastermind 42060 points

    Hello Criton,

    Criton Kallkkaran said:
    Does BQ76952/ BQ79656-Q1 support external circuitry for active cell balancing? 

    Not natively. Active cell balancing would have to be a discrete solution. I have seen some ideas to use the passive cell balancing of our devices as a signal to alert an external circuit. But have not seen a complete design.

    Criton Kallkkaran said:
    Also to add, I could only find BQ76940 battery monitor that does not fall under One-Time Programmable memory. Did I miss any Battery monitors that have reprogrammable memory? Also does BQ76940 support external circuits for active cell balancing? If so could you please share some reference designs?

    The BQ76952 can be OTP'd, but it is not required. You can use an MCU and program on start-up. The BQ76940 does not have any OTP and is not able to do many of the decisions on its own, so it requires more MCU involvement.

    At the moment, TI devices support active cell balancing and there are no reference design for t.

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Prodigy 105 points

    Hello Luis.

    Thank you for your response.

    Luis H. S. said:
    Not natively. Active cell balancing would have to be a discrete solution. I have seen some ideas to use the passive cell balancing of our devices as a signal to alert an external circuit. But have not seen a complete design.

    So that means I could use either of the IC to develop on active cell balancing along with the external circuit. right? 

    Luis H. S. said:
    The BQ76952 can be OTP'd, but it is not required. You can use an MCU and program on start-up. The BQ76940 does not have any OTP and is not able to do many of the decisions on its own, so it requires more MCU involvement.

    Does that mean BQ76952 can be reprogrammed by user?

    Luis H. S. said:
    At the moment, TI devices support active cell balancing and there are no reference design for t.

    Does that mean all the TI battery monitor IC could be used for developing active cell balancing?

    I look forward to hearing from you.

    Kind regards,
    Criton 

  • 0 in reply to Criton Kallkkaran
    TI__Mastermind 42060 points

    Hello Criton,

    Criton Kallkkaran said:
    So that means I could use either of the IC to develop on active cell balancing along with the external circuit. right? 

    In theory you could. 

    Criton Kallkkaran said:
    Does that mean BQ76952 can be reprogrammed by user?

    The device can be re-programmed by the user and/or OTP'd by the user. Both options are available. Some customers OTP the device, other customers program on start-up.

    Criton Kallkkaran said:
    Does that mean all the TI battery monitor IC could be used for developing active cell balancing?

    Whoops! This was a typo! I meant to say "TI devices do not support active cell balancing".

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Prodigy 105 points

    Hi Luis,

    Thank you for the response. I shall see it with BQ76952 and revert.

    Many thanks and Kind regards,
    Criton

  • 0 in reply to Criton Kallkkaran
    TI__Mastermind 42060 points

    Hello Criton,

    No problem! Let me know if you have any additional questions Slight smile.

    Best Regards,

    Luis Hernandez Salomon