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TPS26750: Compatibility with the BQ25758

Santiago Allen
Prodigy 10 points
Part Number: TPS26750
Other Parts Discussed in Thread: BQ25756EVM, BQ25758, BQ25756

Tool/software:

Hi TI Team,

I am looking into a USB C PD setup, and I found some components that I believe to be compatible but could use some advice on. 

From what I am reading I want to use the TPS26750 to make use of its 240W capabilities. The compatible eval boards I am finding reference the BQ25756EVM as the compatible DCDC. 

I like some of the features of the BQ25758 that the BQ25756 does not support and would like to use it. 

I noticed that the register map of the BQ25758 is not exactly the same as the BQ25756 and want to make sure the TPS26750 is compatible with both BQ ICs.

Can you please confirm that it makes sense to use the BQ25758 with the TPS26750.

Thanks.

  • 0
    TI__Mastermind 34676 points

    Hi Santiago, 

    Can you provide details on what kind of application you're looking to design with TPS26750 + BQ25758? 

    Thanks and Regards,

    Raymond Lin

  • 0 in reply to Raymond Lin
    Prodigy 10 points

    Hi Raymond,

    Ideally this would be a two-use design. I want to use the BQ25758 as a standard battery charger, but I also want to integrate it with a TPS26750 and use the design as a USB C charger/discharger. Would it make more sense to use the BQ25756 for both of these applications. In both scenarios batteries would be connected. 

  • 0 in reply to Santiago Allen
    TI__Mastermind 34676 points

    Hi Santiago, 

    I've forwarded this thread to the BQ team for their input. Typically BQ25756 is used for DRP (dual role port) battery charging applications while BQ25758 is more of a DCDC converter. Currently TPS26750 only supports integrated I2C control for BQ25756 and not BQ25758. 

    Thanks and Regards,

    Raymond Lin

  • 0 in reply to Raymond Lin
    Prodigy 10 points

    Sounds great,

    Thanks Raymond

  • 0 in reply to Santiago Allen
    TI__Mastermind 31275 points

    Hello Santiago,

    Thanks for being patient with this. I'm the applications engineer for the BQ2575X family.

    For your application, what features does the BQ25758 have that you would want?

    For charging a single type of battery, I would recommend using the BQ25756.

    If you want to charge multiple batteries with different cell counts, I'd recommend two options. The first is to use the BQ25758 and select the charge voltage with I2C. You'll need a microcontroller to control the fast charge setting, precharge setting, charge voltage, and termination current. The 2nd is use the BQ25756 with a digital potentiometer on the FB pin. A microcontroller can select the different charge voltages by controlling the digital potentiometer.

    Let me know if you have any questions about this.

    Best Regards,
    Ethan Galloway

  • 0 in reply to Ethan Galloway
    Prodigy 10 points

    Hi Ethan,

    Thanks for the reply. For the application I have in mind this would be a USB C charger/discharger that could work with a voltage range of batteries. For this it sounds like I would want to go with the BQ25758 to set the charge voltage on the go via I2C, and from what I am understanding the TPS26750 does not support writing to the voltage set registers and would require the additional support of a microcontroller to do so? Were as the BQ25756 requires a pin to be configured to set charge voltage? For context I plan on having a microcontroller on the I2C bus regardless. 

  • 0 in reply to Santiago Allen
    TI__Mastermind 31275 points

    Hello Santiago,

    Thanks for the new information.

    Santiago Allen said:
    from what I am understanding the TPS26750 does not support writing to the voltage set registers and would require the additional support of a microcontroller to do so?

    Yes, this is correct. A microcontroller would need to write the charge voltage setting of the BQ25758 and also terminate charging once the charging is done.

    Santiago Allen said:
    Were as the BQ25756 requires a pin to be configured to set charge voltage?

    Yes, a feedback network on the pin of the BQ25756 will set the charge voltage.

    Let me know if you have any other questions.

    Best Regards,
    Ethan Galloway