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HD3SS3220: DFP, GPIO mode

Mateusz K.
Prodigy 10 points
Part Number: HD3SS3220


Hi,

I am working on external interfaces to the SOM module (NXP i.MX8M), I need to make USB 3.0 implementation as simple as possible on the USB C connector (DFP mode, no additional functionality such as charging, audio, etc.). I would like to use the HD3SS3220 chip in GPIO mode plus a simple USb VBUS switch chip (STMPS2171).

The question is: what signal should control the switching of VBUS voltage? If I connect it as shown in the diagram below, power will be available to the receiver constantly.

  • 0
    TI__Guru**** 181321 points

    How is the ID pin of the HD3SS3220 being connected? The HD3SS3220 monitors the voltage level on the CC pins looking for the R(d) termination of a UFP. When a UFP is detected and HD3SS3220 is in the attached. SRC state, the HD3SS3220 pulls the ID pin low to indicate to the system the port is attached to a device (UFP). So you should able to use the ID pin, going from high to low, to enabled the external power switch.

    Thanks

    David

  • 0
    TI__Guru 64326 points

    Hi,

    The EN pin of your Power switch can be controlled by the ID pin of HD3S3220 for this application.This will enable VBUS to flow when HD3SS3220 sees an device attachment over the CC line. Be sure to consider EN pin polarity compatibility with ID pin in this case. You could also connect ID to a GPIO and allow your processor to make the decision on whether VBUS should be enabled.