TUSB211RPTREVM: Eye Diagram is not improving

Hi Zach,

Please make sure that it is following the application procedure detailed in the TUSB211 datasheet. Also, the application note (SLLA593 - High-Speed Signal Quality Test Modes) would be helpful for the your reference. Please let me know any updates.

Regards,

Josh

Hello Josh, 

Following the datasheet and the HS application note, our performance actually degraded with the EVM. In most EQ cases, the top line of the eye diagram dropped into the red area (closer to .3) on the scale. The eye diagram actually looked the best with the device disabled. Are there applications where the TUSB211 can't be the solution? I'm just curious if this is where we are at. 

Thanks,

Zach

The result is unexpected. I don't think the device is in test mode.

please see below test sequence is important.

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/469595/tusb211---not-activating

how are you disabling the device? I assume you are removing the device.

We're following the embedded host procedure that is located in application note SLLA593. We've removed the device and also kept the device in reset. Both look like similar waveforms on the eye diagram. 

When we follow the embedded host set-up though, our HS green LED does not come on after the CD amber LED. Why would that not happen? 

Thanks,

Zach

Hi Zach,

How long is the cable length for the test?

I was wondering if you could potentially switch to the TUSB216I, as it is more up to date and could boost performance even more. For your reference, you can find a datasheet and guide to replacing a TUSB211 if needed. (TUSB216I)

Regards,

Josh

HI Josh,

The cable length for the test is short respectively ( < 6"). We are considering a longer cable for the actual design (2'). Is there any way that I could get a TUSB216 evaluation board sent to us for the short-term test if you feel that this a better option?

Thanks,

Zach

It is not recognizing the high-speed test pattern. So it is not activating boost. which embedded test fixture and test ID drive are you using?

As with all prior modes of testing, both CD and ENA_HS are low initially. Upon connection of the VID/PID test host device (Step 6), the CD flag switches high (Figure 4-2). Shortly following this, after successful enumeration by the embedded host, ENA_HS also switches high (Figure 4-3). If this does not occur, ensure that the VID/PID device is active and presenting the correct VID/PID combination. For some system setups, the embedded host must be powered on prior to the VID/PID device to properly enumerate it. Also ensure the relay board is set to the "init" position to support handshaking

at this point the ENA_HS needs to be high before taking eye diagram

Please make sure to get this one.

https://www.ti.com/tool/TUSB216IEVM