TUSB544: [TUSB544] AC capacitor on the TX and RX lanes

Maurice Brunel

Part Number: TUSB544
Other Parts Discussed in Thread: TUSB564

Hello,

In the Typical Application Circuit in the datasheet to the TUSB544 component, there is AC capacitor on the RX lanes. Why ? Isn't it just on the TX lines? So, for my application I use one RX lane to USB 3.0 (toward HUB USB) and one RX lane to DP (toward display controller). You can find below a link toward the datasheet (schematic is on the page 25) and a picture of the schematic.

https://www.ti.com/lit/ds/symlink/tusb544.pdf?HQS=dis-dk-null-digikeymode-dsf-pf-null-wwe&ts=1657722954461&ref_url=https%253A%252F%252Fwww.ti.com%252Fgeneral%252Fdocs%252Fsuppproductinfo.tsp%253FdistId%253D10%2526gotoUrl%253Dhttps%253A%252F%252Fwww.ti.com%252Flit%252Fgpn%252Ftusb544

Thanks & best regards,

Maurice Brunel

over 2 years ago

+1 Brian Zhou over 2 years ago

TI__Guru** 113045 points

Maurice :

on the connector side, normally place AC cap on TX side since there is AC cap on TX side from the other connector, so there is always 75nf-265nf Ac cap between TX and RX.

If you connect TX and RX directly to host like you mentioned above in red, just place AC cap 75-265nf on both TX and RX.

Regards

brian

0 David (ASIC) Liu over 2 years ago in reply to Brian Zhou

TI__Guru*** 149885 points

Hi, Maurice

Is this a USB Type-C application which you will have a separate USB host and DP source? If this is the case, then you should use TUSB546 instead TUSB544.

Thanks

David

0 Maurice Brunel over 2 years ago in reply to David (ASIC) Liu

Prodigy 70 points

Hi David,

On the right side I have a USB-C connector to connect a smartphone for example and on the left side I have a HUB USB and display controller. I can juste send the data toward the display controller and I can't received it, and I can send and receive the data with the HUB USB.

Maurice

+1 David (ASIC) Liu over 2 years ago in reply to Maurice Brunel

TI__Guru*** 149885 points

Maurice

It looks like you are designing a USB-C sink application. For this application, you would then need the TUSB564 as it will MUX out the USB signal to the USB hub or the DP signal to the DP controller depending the CC negotiation.

Thanks

David

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TUSB544: [TUSB544] AC capacitor on the TX and RX lanes