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TPS65987D: How could PD control Buck-boost Charger?

Jim CHEN
Expert 4795 points

Part Number: TPS65987D
Other Parts Discussed in Thread: BQ25703A

Dear Team,

My customer would like to use TPS65987D +Buck-boost charger for their Type-C design.

Their Source/Sink PDO are as below.

Source PDO: 5V/3A, 9V/3A

Sink PDO: 20V/3.25A

If they only want to use one internal power path for both Source/Sink PDO, how TPS65987D control Buck-boost charger? Is there any application note for such application?

Is there any timing problem to support PD compliance testing and Fast Role Swap?

Thank you.

Regards,

Jim

  • 0
    TI__Mastermind 36756 points
    Hi Jim,

    The TPS65987D can control the BQ25703A or other buck/boost chargers through I2C to meet your requirements. It's important to ensure 5V is available on PPHV when the TPS65987D is expected to source.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    TI__Expert 4795 points
    Hi Eric,

    I found that there are two application notes that could meet my requirements.

    www.ti.com/.../tidue65a.pdf
    www.ti.com/.../slvae18.pdf

    In above documents, PD is I2C master and controls the charger.
    But in my customer case, due to charger still require Gauge's battery information from EC. EC must be I2C master instead of PD to control charger. So EC needs to read the PD register and write the register of charger.

    I would like to know whether the timing delay between PD, EC and charger cause any problem when doing CC communication or not. For example : Power Role Swap or Fast Role Swap.

    Thank you.
    Jim
  • 0 in reply to Jim CHEN
    TI__Mastermind 36756 points
    Hi Jim,

    That's correct. In that case the EC would need to be the I2C master. There is a risk of having issues with FRS with this architecture. There must be 5V ready to source when the NB does the FRSwap. There should be no issues with a Power Role Swap since the timing requirements are not so difficult to meet.

    Thanks,
    Eric