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TIDA-050047: Portable solar power bank with USB-PD

Ondrej Deingruber
Prodigy 10 points
Part Number: TIDA-050047
Other Parts Discussed in Thread: BQ25798, USBCPD-APPLICATION-CUSTOMIZATION-TOOL, TPS25750, TPS25751, TPS2121

Tool/software:

Hello,

This reference design covers a lot of things I want to do but does not incorporate solar charging, the BQ25798 should be capable of MPPT solar charging, but I don't see how to incorporate solar panels into this design. Is it possible to modify it to enable solar charging as well?

my system requirements:

The solar array should have about 25W peak power. The battery does should be at least 3000 mAh at 3.7V but not more that 10000 mAh at 3.7V. (weight limited)

The power bank should be able to charge devices and be charged with USB-PD. The solar charger controller should use MPPT algorithm.

In the best case, no programming should be nercessary (for example configuration via USBCPD-APPLICATION-CUSTOMIZATION-TOOL).

do you have any solution that covers this requirements easily? I was looking trough the reference designs and evalueation board but none covered my specific use case.

Thanks

Ondrej

  • 0
    TI__Guru**** 169036 points

    Hi Ondrej,

    BQ25798 has fractional open circuit MPPT feature (periodically resetting VINDPM=VOC*% based on panel's sampled VOC) that can be enabled via I2C write to the EN_MPPT bit.  The EN_MPPT bit resets with WD timer expiration, complete POR or battery voltage discharging below the MINSYS voltage.  So at a minimum, the USB-C PD firmware would have to be modified to set EN_MPPT =1 for a solar only application.  If the battery is allowed to discharge below MINSYS voltage, ideally, the firmware would also need to sense that event and rewrite EN_MPPT=1 once the battery charges above MINSYS. 

    I will reassign back to the USB-C PD team for comment.

    Regards,
    Jeff

  • 0 in reply to Jeff F
    TI__Mastermind 37655 points

    Hi Ondrej,

    From the USB-C PD side of things, there are a couple of comments.

    1. No new designs should be using the TPS25750. We are in the process of updating the CHG-EVM (TIDA 050047) to support the TPS25751, which is a pin to pin in replacement.
    2. The TPS25751 needs an external fw image loaded on boot up. This can either come from an EEPROM, or an EC/MCU can program the device over I2C. The CHG-EVM uses the EEPROM. The external image is generated by the USBCPD-APPLICATION-CUSTOMIZATION-TOOL and is required.
    3. The CHG-EVM system is designed with the TPS25751 controlling the BQ25798 over I2C. The TPS25751 configures initial settings on power up, and configures the BQ device appropriately when sourcing and sinking. It does not support programming the MPPT feature.
      1. Because of this, we would not recommend you have the TPS25751 as the I2C controller of the BQ25798, and instead control both with your own EC/MCU.

    Thanks and Regards,

    Chris

  • 0 in reply to Christopher Lim1
    Prodigy 10 points

    Hi Christopher,

    Thank you for the reply.

    So if I understand this well, I can use a design similar to TIDA 050047 but with TPS25751 and I need to have external microcontroller to control both the TSP25751 and BQ25798. Does TI offer different charger that supports both USB-PD and MPPT?

    Regards,
    Ondrej

  • 0 in reply to Ondrej Deingruber
    TI__Mastermind 37655 points

    Hi Ondrej,

    I support the PD controller products and there is not a device that does both. I'm not sure about the Battery Charger portfolio, so will send this thread back to the BQ team.

    Thanks and Regards,

    Chris

  • +1 in reply to Christopher Lim1
    TI__Guru**** 169036 points

    Hi Ondrej,

    BQ25798 is your best option.  Instead of using the BQ25798's ACDRV1/2 to switch external back-to-back FETs between different USB-C and solar panel input sources, another customer is using TPS2121 MUX IC.  

    Regards,

    Jeff