HD3SS3212: AC CAP

Hi,

Could you share the part used for CC Contrller with mux? Does this part mux the USB 3.0 data lanes and the CC lines (HD3SS3220)? For HD3SS3212 the AC coupling should be place closest to the connector (blue arrow) not near the USB Host. This allows the host to bias HD3SS3212.

Hi Sirs,

Thanks for you reply.

Our CC Controller with mux is use Realtek RTS5451.

We know TI have HD3SS3220 but unfortunately Realtek is end customer consign parts that why we couldn't change it.

We have two idea on AC CAP replace.

Could you help check which one are more suitable for us?

1. As the yesterday picture. if we put AC cap on red and blue side both, have risk?

2. Follow as below

By the way, The final schematic will choose HD3SS3212 or TUSB542, so is there any topology different between HD3SS3212 and TUSB542?

Hi Sirs,

Could you please help to review attached schematics for replacing HD3SS3212 with TUSB542 ?     And please also kindly help us to review if the CNFG settings are fine for driving strength ?!

Schematic:

Hi,

Before I review, is the customer planning on "dropping" in TUSB542 in HD3SS3212 place (no schematic change)?

Hi,

The schematic is fine. The CNFG pin settings would depend on the expected loss of your pre-channel and post-channel. What is the expect loss for your pre-channel and post-channel? 

Hi Sirs,

Thanks for your reply.

According our EA measurement , the USB3.0 V-swing is about 65mV~80mV , and it should be 100mV minimum on SPEC.

In type-c host mode , we can use intel PLEVT tool to tunning de-emphasis level from default 65.1% down to 42.9% , then can measured USB3.0 V-swing level raised up to 109 mV, and pass the test.
In type-c device mode , we only have the first time mearsurement result , which level is 65.1% , and failed as well.

If we expect USB3.0 Swing could have at least 115mV above , how should we to set these CNFG pins ?

Thanks a lot.

Hi Sirs,

Sorry to pushed, have any update on this case?

Thanks!!

Hi,

You should try CNFG_A2 = Float and CNFG_B2 = Float. This will set the transmitted output swing to 1.1 V and give 3.5 dB of DE tot eh output signal. What is the distance between TUSB542 and the connector? 

any update?

Hi Sirs,

Thanks for your reply.

Please refer below figure as the distance between CONN & re-driver.  They are closed but on different layer (TOP/BOT).

 did you try CNFG_A2 = Float and CNFG_B2 = Float?

Hi Sirs,

Thanks for your reply.

Could you help to review attached file as TUSB542 schematics for TYPE-D DP port new topology ?

And please check if the AC coupling caps placement is good for TUSB542.

 Schematic:

Function block:

Shu-Cheng

Do you have AC caps on USB3_TC_TXP/N1 and USB3_TC_TXP/N2?

Is it possible to provide the schematic including the full data path from USB3380 all the way to the Type-C connector make sure everything is correct?

Thanks

David

Hi Sirs,

Thanks for your reply.

Please refer to attached file as our final design. We placed 0 ohm (0201) on CPU side , and AC caps are located between TUSB542 and CONN.

Do you suggest to replace 0 ohm with AC caps on CPU side ?

Schematic:

By the way, Here is the USB type-c topology of our design for you to reference.

Currently, we add the ac coupling before TUSB542 and type-c connector.

Please help to check again. Any suggestion is welcome. Thanks!!

Hi,

TUSB542 does require AC coupling on both sides, in between HD3SS3212 -->TUSB542 and TUS542 --> connector. AC coupling cap should be placed in the schematic. In your current configuration above HD3SS3212 does not need AC caps between USB host and HD3SS3212. TUSB542 CNFG pin config depends on the expected losses of the pre and post channel in you system. If you give me trace lengths, I may be able to give you a better starting place. Keep in mind that in this application there is a potential for the optimal settings to differ for CNFG_x1 pins based on the path selected in HD3SS3212. 

Chenglin:

   any update?

Hi Sirs,

Thanks for your reply.

Update the trace length of U3 topology. There is a 2.5 inch internal cable to connect MB to IO BD.

Could you please give us some suggestion about TUSB542 CNFG setting?

Thanks!!

Hi Sirs,

Sorry for pushed, have any update on here?

Thanks!!

did you try above setting?

Hi Sirs,

We've pass the USB3.1 gen1 5G test on DVT MB with TUSB542.

Thanks for your help.