TUSB1046A-DCI: TUSB1046AI-DCI EQ configuration on GPIO mode

Hi Logan,

Since you're using the TUSB1046 you want to only use the (linear redriver) tabs in this tool. The limiting redriver tabs will not be relevant.

You can start with the RX Budget tab. This will have editable fields to account for the channel that receives data from the USB-C receptacle. Once you've added your design parameters into this section of the tool, it will give a recommended EQ value in the blue cell at the center-bottom of the page. You should set your EQ close to this value for a good starting point in your design. I put example parameters for a design that uses the TUSB1046 in the image below with descriptions of each field:

Note that this recommendation should be taken as a starting point (not as the perfect EQ value). Once the design is actually fabricated it may still be necessary to tune the EQ for best results.

The TX budget tab is similar to the RX budget tab, however this tab accounts for the channel that transmits data into the USB-C receptacle. This tab would give you a good starting point for the SSEQ setting on the TUSB1046.

Logan said:

how to configure the resistor pull up or pull down (GPIO mode)?

The image you show is a good implementation for resistor pullups/pulldowns on the EQ settings of our device. In general, we recommend having the option to both pull up and pull down each EQ settings so you can tune the EQ as needed once the board has finished fabrication. The purpose of the RX/TX budgeting tool is to check whether the system design is realistic for passing USB compliance and to give a recommended starting EQ value.

Let me know if you have any questions.

Best,

Shane

Hi Logan,

Yes you can use the TX budgeting tab for DPEQ settings. Just be sure to lower the data rate from 10G to 8.1G.

Logan said:

"Pre-channel FR4 trace length =1 " is mean that layout routing the length of TUSB1046 to the USB-C receptacle fixed at 1 inch?

Yes, you want to put the trace length between the TUSB1046 and the USB-C receptacle in this cell so we can calculate the appropriate EQ:

If the recommended RX EQ (Blue Cell) is black as shown in the image you've sent, then the channel is too lossy for our TUSB1046 to compensate. I recommend using a lower loss material, reducing the trace/cable length, or reducing the number of vias until there is a number in this cell

Best,

Shane

Hi Logan,

"RX Max CTLE" is the maximum EQ your USB Host can provide. This is not related to the TUSB1046, but is good to know because the USB host and re-driver work together to compensate the RX path in a USB connection.

For example, if you have a long/lossy RX channel that the re-driver cannot fully compensate, a USB host with RX equalization may be able to recover the USB signal. In a system where a linear re-driver is near the USB-C receptacle, it is often the USB host that needs to compensate the majority of loss on the RX path. Please see this E2E FAQ for more info.

"CTLE compliance spec @ receptacle" Is the amount of EQ needed to compensate any cable/fixture that is attached to the Type-C receptacle. If you want to be able to support longer or higher loss cables on the Type-C receptacle, you can increase this value to check whether your system will compensate enough loss. I recommend keeping a baseline of at least 2dB.

Best,

Shane