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Original question:

TPS25821: CHG function of USB2.0/3.0

TPS25821: TPS25821 / current limit on USB3.1 port

Alen Barisic
Intellectual 1300 points
Part Number: TPS25821

Hi Team,

we have tested TPS25821 with CHG pin set to “0” on a USB 3.1 port and we still have 900mA of current (limiting). Shouldn't it (due to the missing VCONN power switch) have a current limit of 500mA for all cases (USB2.0 and USB3.1)?

For our application we want to limit the charging current to 500mA for all cases (including USB 3.1). Is there a way to do this with the TPS25821? If not, are there any other devices or workaround to achieve that?

Thanks a lot!

Alen

Circuit:

  • 0
    TI__Mastermind 32280 points

    Hi,

    Thank you for reaching out. I will look into this and get back to you as soon as possible.

    Regards.

  • 0
    TI__Mastermind 32280 points

    Hi,

    When CHG is set to 0, the CC capability broadcast is set to STD and the current broadcast depends on what type of port is used (900mA for USB 3.1 ports and 500mA for USB 2 ports). Based on the datasheet, I do not think TPS25821 can limit the charge current to 500mA for all ports.

    To achieve the goal of limiting charge current to 500mA for all cases, I will check with my team to make sure if we have device or work around that can achieve this.

    Regards

  • 0 in reply to Tommy Lin
    TI__Mastermind 32280 points

    Hi,

    TPS25821 and all our devices are designed to meet the spec of USB2 and USB3.

    Does your customer plan on applying for any certification or pass any compliance? Limiting the the current to 500mA for USB3.1 will not pass the compliance.

    If your customer does not plan to pass compliance and apply for certification, the workaround can be adding a current limiting switch to VBUS to limit the current to 500mA.

    Regards.