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Original question:

USB-PD-CHG-EVM-01: High Power USB-C Power Path charging IC for 5s Lion Battery Pack Suggestion

BQ25730: System Reference Design

Roy Yang
Prodigy 50 points
Part Number: BQ25730
Other Parts Discussed in Thread: LM5155, TPS25750

Hi,

I am designing a device that run off a 5 to 6 cells of Lion 18650 batteries (18-21.6v 2600mah per cell). I am looking into using USB-C interface (20v 5A 100w) to power the load as well as charging the batteries. The system load will be operating 48v to 54v.

A few specifications regarding my design:

  • Max output power 100w
  • Max input power 100w
  • Battery: 5-6s Lion 18650 batteries (18-21.6v 2600mah per cell)
  • Power Path for charging while using
  • USB-C charger: 100w 20v 5A
  • Battery could power the system without having a USB-C charger plugged in 

And after looking at the reply on my last post, I'm planning to use BQ25730 as the charger IC since it support 5s and power path. And LM5155 to boost the output voltage to 48 to 54v. Here are a few questions I encountered:

  • Can I use TPS25750 as the PD controller to negotiate 20v 5A?
  • Do I need a Furl Gauge?
  • Do I need a MCU for normal operation? If yes, any recommendations?
  • How to I balance the cells voltage while charging? Does it require a specific IC? Can I use a off the shelf BMS?
  • Is there any related system diagram?

Much appreciate in advance.

Roy

  • 0
    TI__Genius 11385 points

    Hi Roy,

    Thanks for considering BQ25730 in your design. First I want to note that there are different teams supporting different TI ICs. Our group only supports the charger. For non-charger related questions, you will have to post separate E2E threads with the right IC name in the title.

    Here are my answers to your question:

    • Can I use TPS25750 as the PD controller to negotiate 20v 5A?

      BQ25730 is a I2C slave device. It can operate for the 20V range if the master sets the appropriate settings. So, in theory, TPS25750 can support it but you have to confirm it with the TPS25750 team (submit a separate E2E thread with TPS25750 on the title).

    • Do I need a Furl Gauge?

      I personally recommend battery protector/monitor/gauge IC for any battery operated systems. 

    • Do I need a MCU for normal operation? If yes, any recommendations?

      Yes, you need MCU for BQ25730 operation because the IC defaults to 0A charge current until it gets changed by the MCU. You will need to post a different thread so the embedded experts within TI can provide you with recommendations on MCU selection.

    • How to I balance the cells voltage while charging? Does it require a specific IC? Can I use a off the shelf BMS?

      To my knowledge, some gauge type ICs can cell balance. You will need to post a different thread so the gauge experts within TI can provide you with IC recommendations.

    • Is there any related system diagram?

      Unfortunately, we do not have a system diagram as those could sometimes be very application specific and varies a lot.

    Thanks,

    Peng