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How to detect the current capability of a USB upstream port or charger - USB2/3 or USB-C

Rob Strange
Prodigy 140 points
Other Parts Discussed in Thread: TUSB320, TPS65987D

Hi,

I am designing a commercial handheld device which needs to charge from USB.  I also need USB2 data to a host processor.

The current aim is a USB C connector, although I may not have much control over what the end user plugs it into.

I understand that various charging current are available - 500mA of USB2, 900mA for USB3, 3A for USB-C.  I want to charge at a minimum of 5V/1A where that is available.

I have a charger which can be programmed with the desired charge current by the host processor, although the charger itself cannot detect all those different current capabilities.  So far as I can tell, the host processor's USB port can detect a charger, but not its capability.

What I am missing is that presumably there needs to be a device on the USB D+/D- lines and likely to USB C CC lines to detect the charger capability.  However, I am having difficulty identifying what chip or chips those might be.  So far, the chips I have found are either intender for the charger-end of the cable, or detect the charger without divulging its capability.

Can you point me in the direction of the correct parts, please?

Thank you.

  • 0
    TI__Mastermind 28160 points

    Hello Rob,

    Thanks for posting your question here on E2E. There are a few different ways you can approach this.

    1. You can use a USB Type-C CC port controller like the TUSB320 in addition to a BC1.2 port controller to negotiate power. You will have to find and implement an external power path to connect to your internal PMIC or BQ devices.

    2. You can use an all in one Type-C PD controller like the TPS65987D which integrates Type-C, BC1.2, and an internal power path all into a single IC. This a Type-C PD controller, so only sinking 5V/3A may be a bit over kill, but it may be the simplest implementation.

    Either approach would yield the same results so it would just be personal preference on which route you would like to take.

    Let me know if this helps answer your question or not!

  • 0 in reply to Adam Mc Gaffin
    Prodigy 140 points

    Thanks for the reply, Adam.

    Sorry for the delay in replying - didn't realise I'd not got back to this!

    Looks like my CPU is better at negotiating than I'd realised, so that, plus the TUSB320, may be what I require.

    Thanks for your help.

    Rob