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HD3SS3220: Schematic_review

Yasar Maheen Seenath
Prodigy 250 points

Part Number: HD3SS3220

Tool/software:

Hello Team,

Could you please help to review the attached schematic of 'hd3ss3220" CC controller. (hd3ss3220_schematic.pdf)

hd3ss3220_schematic.pdf
As our SoC/PMIC doesn't have CC support, we have come across the use case of an external CC controller, which is hd3ss3220.
Attached the block diagram (USB.pdf) of proposed USB implementation section.

8255.USB.pdf

As per our design requirement, we should be able to operate the Type-C port in both DEVICE and HOST mode.
Hence considered implementation will be the DRP option of hd3ss3220.


By default SoC configuration, USB0 port will be in Device mode, and should be able to flash the firmware via Type-C port.
As per my understanding, VBUS_DET will serve that purpose upon detection of VBUS power from an external host PC, and we can operate in "DEVICE" mode.

Now the query is, how hd3ss3220 control the switching from DEVICE to HOST mode.
Is "ID" pin of hd3ss3220 will perform that operation?
(As mentioned in datasheet, ID pin---asserted LOW when CC pin detected device attachment when port is a source)

Can I map the "ID" pin of hd3ss3220 to an SoC GPIO, to configure the SoC's USB controller to HOST mode?
(based on the ID pin's logic change upon detection of HOST device attachment at USB connector)

  • 0
    TI__Guru 59295 points

    Hi Yasar,

    Yes, the ID pin needs to be attached to the SoC, that way it can communicate changes in the role, as well as when the SoC should be sending VBUS, so that it is not sent too early. It should wait until the ID pin goes low to send VBUS.

    It looks like you are using this level translator to communicate this, please make sure it is configured correctly for communicating when ID is low.

    For the overall schematic, I see what looks like a few switches in series:

    For these switches, while it is okay to have 330nF capacitors on the RX lines, you should not have 220nF capacitors for TX on each side of the mux. Additionally, the overall capacitance on the TX lines should ONLY be either 100nF or 220nF. You do not need both on a TX line.

    For VCC, we recommend a 100uF VCONN bulk cap and a 100nF cap. I don't believe I see either of these in this schematic.

    Please let me know if you have any other questions.

    Thanks,

    Ryan