TUSB522P: Connection pinout

Griffin Burns

Part Number: TUSB522P
Other Parts Discussed in Thread: TUSB542, TUSB544

Hi, i haven't worked with USB3.0 before and i have a novice question on the Tx/Rx connections coming from the host (upstream) and then connecting to the downstream device.

Based on the block diagram figure 7.2 it seems logical to me to have the following the connection:
host Tx -> Rx1
host Rx <- Tx2

Rx2 <- SoC Tx
Tx1 -> Soc Rx

However, every reference SCH i've seen has the following:

host Tx -> Tx2
host Rx <- Rx1

Rx2 <- SoC Tx
Tx1 -> Soc Rx

i marked up the block diagram showing what i think the connection would be. This connection does not match ref schematics but i can't understand why a Host Tx would route to a transmitter and not a reciver

15 days ago

0 Griffin Burns 15 days ago

Prodigy 30 points

0 Vishesh Pithadiya 14 days ago in reply to Griffin Burns

TI__Guru 54276 points

Hi,

When using a Type-B receptacle with a USB redriver. You can route the pins labeled TX to the TX pins of the part and the pins labeled RX to the RX pins of the device. This is due to the naming of the pins on the connector. The data direction is consistent.

Your understanding of data direction is correct.

0 Griffin Burns 14 days ago in reply to Vishesh Pithadiya

Prodigy 30 points

just so it's clear to me, i suppose this is also true with a USBC cable? TX to TX, RX to RX?

0 Vishesh Pithadiya 14 days ago in reply to Griffin Burns

TI__Guru 54276 points

We can do a schematic review once you are at the stage.

The key is to make sure the data direction is consistent across all components in the system.

If you are using a USB Type-C connector, you need a crossbar mux such as the TUSB542 to handle both normal and flip directions. Can you share a BD for your design?

0 Griffin Burns 14 days ago in reply to Vishesh Pithadiya

Prodigy 30 points

here is a snippet from a previous project which I've been told, "is working"

Host side USB cable is connected to RX1/TX2
Downstream SoC is connected to RX2/TX1

0 Vishesh Pithadiya 14 days ago in reply to Griffin Burns

TI__Guru 54276 points

Yes in this case we can see that the input port is a Type-B connector, so this should be ok.

Please share your type-C schematic once ready. USB Type-C has a few more considerations that standard Type-A or Type-B. You must consider the flip orientation as well.

0 Griffin Burns 14 days ago in reply to Vishesh Pithadiya

Prodigy 30 points

thanks for the help Vishesh. here is the current USBC schematic. Please note, that this rev has a connector mistake. The Tx nets should be on TX1 of J1A

0 Vishesh Pithadiya 14 days ago in reply to Griffin Burns

TI__Guru 54276 points

Yes the data direction looks ok here. Will CTX2 and CRX2 be used in this design? Or will this be a fixed orientation USB Type-C connector?

0 Griffin Burns 14 days ago in reply to Vishesh Pithadiya

Prodigy 30 points

I'm not the lead designer for this SCH but i'm told CTX2 and CRX2 will NOT be used so a fixed orientation on USBC will be needed. I'm asking my coworker if he plans to add a second redriver to increase the bandwidth and cover RX2 and TX2

0 Vishesh Pithadiya 14 days ago in reply to Griffin Burns

TI__Guru 54276 points

Got it.

If you do end up using CTX1/2 and CRX1/2 You can have a look at the TUSB542, and the TUSB544. I believe these would be appropriate for your application.

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TUSB522P: Connection pinout