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BQ25792: TPS25750: appropriate combination of TPS25750 and Charger IC, i.e. BQ25792

Part Number: BQ25792
Other Parts Discussed in Thread: TPS25750, , BQ25790, BQ25713, BQ25731, BQ25720, BQ25730, BQSTUDIO

Hi

I am designing the electronics for a mobile device.

Here some facts&requirements:

  • powered by a  SMBus Battery pack 4S2P Li-Ion cells (RRC 2054-2)
  • Load current at VSYS up to 3A
  • max. charge current 3.8A
  • standalone solution required (no SW)
  • the device gets recharged by a USB-PD charger max. 100W
  • low standby current
  • USB-PD in Dual-Role (Sink with max. 20V/5A and Source with 5V/max.3A)

The TPS25750 together with BQ25792 look like the perfect solution.

Or is there a more approbriate combination of TPS25750 and an other version of Charger IC?

The TPS25750 Application Customization Tool lists only the following ICs:

  • BQ25790 or BQ25792
  • BQ25713
  • BQ25731

Is there any combination of USB-PD Controller and an SMBus-compatible Charger-IC to make use of the SMBus Broadcasts ChargingVoltage and ChargingCurrent ?

Any suggestions welcome!

  • Hi Reinhard,

    In theory, the I2C controlled TPS25750 can be used with any charger.  The I2C controlled chargers listed above are the only ones for which TPS25750 firmware has been developed.  If you can use an I2C controlled charger, with load current of 3A and charge current of 3.8V, I recommend BQ25731 instead of BQ2579x. There is an SMBUS version of BQ25713, BQ25720, which could work.  The TPS25750 team will have to comment on whether it is possible to develop TPS25750 firmware for an SMBUS charger like BQ25720.

    Regards,

    Jeff

  • Hi Reinhard,

    As far as I know, there are no current plans to add more BQ devices to the GUI, but there may be options for configurations done by the customer. Let me reach out to a team member more familiar with the BQ parts and see what the options are. Please expect a delay due to people being out for the holidays.

    Thanks and Regards,

    Chris

  • Hi Reinhard,

    We only support BQ257xx parts listed in our Application Customization Tool (BQ25790/2, BQ25731, and BQ25713). Based on requirements, there are certain BQ257xx parts to select: 

    For parts not listed (such as BQ25720) we do not have the firmware to support the I2C. If the unsupported part has similar registers and same pinouts as supported parts, then it could be possible to still use it, however it might require an EC or other IC device to set certain registers. Please refer to this e2e thread about BQ25730 support for more information: https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1015777/tps25750-can-we-use-tps25750-bq25730-for-an-integrated-battery-charging 

    For integrated PD+BQ solution, I recommend choosing from the available options. Other BQ parts will require workarounds, such as adding in an additional EC or gauge. 

    Thanks and Regards,

    Raymond Lin

  • Hi Raymond,

    why can´t we use the BQ25790 with integrated FETs for a battery powered system > 45W ?

  • Hi Reinhard,

    Raymond and I primarily support the PD controller, so it may be better to ask this question to the BQ team.

    From my understanding, when the BQ25790 pushes past 45W, there are concerns with thermal shutdown.

    If you need more information on this particular issue, I would recommend reaching out to the BQ team.

    Thanks and Regards,

    Chris

  • Hi Reinhard,

    Chris is correct.  The BQ25790 package can't dissipate more than 45W.  After that, the charger enters thermal regulation and limits the output power.

    Regards,

    Jeff

  • Thank you,understood so far .

    I have 2 more questions:

    1. Can we use the charger-IC without direct connection and configuration to/from the USB-PD controller?

        Which registers of the charger-IC are configured by the USB-PD controller ?

    2. Is it possible to configure the 5V-Source path of the USB-PD controller to less than 3A, i.e. 1A ?

  • Hi Reinhard,

    1. Can we use the charger-IC without direct connection and configuration to/from the USB-PD controller?

        Which registers of the charger-IC are configured by the USB-PD controller ?

    Configuration wise yes you can do so but since BQ25790 is a host-interfaced device you will need an external MCU to configure it.

    Please refer to the datasheet and EVM user's guide (test procedure) for BQ25790 registers that needs to be configured. We have a GUI, bqStudio, that can be used for the configuration.

    2. Is it possible to configure the 5V-Source path of the USB-PD controller to less than 3A, i.e. 1A ?

    It is possible but the default contract (specified in the USC-IF documents) still needs to be 5V3A. Once the 5V3A contract is established between the source and the sink then you can lower the current capability.

    Regards.