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HD3SS3220: HD3SS3220 Does Not Care About Differential Pair Polarity

Conor
Mastermind 8890 points
Part Number: HD3SS3220

Tool/software:

Hi,

I am considering a circuit configuration to use HD3SS3220 in UFP mode.

Q1. When using in UFP mode, am I correct in thinking that the TX pin of the USB multiplexer and the TX pin of the USB Type-C connector are connected?

In the EVM in DFP mode, the TX pin of the USB multiplexer and the RX pin of the USB Type-C connector are connected, and I am confused.

Q2. The following note was written in the block diagram of the data sheet.

Note: HD3SS3220 Does Not Care About Differential Pair Polarity

Q2-1. Am I correct in thinking that it can be connected without being aware of Posi and Nega?

Q2-2. If I connect without being aware of Posi and Nega, will this affect the Txp/Txn and Rxp/Rxn pins on the left side?

Q2-3. Do I need to be aware of Posi and Nega for the Txp/Txn and Rxp/Rxn pins on the left side?

Thanks,

Conor

  • 0
    TI__Guru*** 149885 points

    Conor

    Q1. When using in UFP mode, am I correct in thinking that the TX pin of the USB multiplexer and the TX pin of the USB Type-C connector are connected?

    In the EVM in DFP mode, the TX pin of the USB multiplexer and the RX pin of the USB Type-C connector are connected, and I am confused.

    Both are correct. The HD3SS3220 is a passive switch, so it is possible to swap its TX & RX pins, you only have to care about the appropriate routing direction between the HOST and the connector.

    Q2-1. Am I correct in thinking that it can be connected without being aware of Posi and Nega?

    Q2-2. If I connect without being aware of Posi and Nega, will this affect the Txp/Txn and Rxp/Rxn pins on the left side?

    Q2-3. Do I need to be aware of Posi and Nega for the Txp/Txn and Rxp/Rxn pins on the left side?

    Per USB3 specification all the USB PHYs must detect and compensate any polarity inversion, so you can flip the polarity at both sides of the HD3SS3220.

    Thanks

    David