TUSB212: Urgent disconnecting issue of tusb212

Hi Nan,

1.) Could you possibly send eye diagrams captured at High DC Boost and Medium DC Boost? I would like to see how the eye diagrams compare.

2.) Are eye diagrams between working boards and problem boards similar? Is there any noticeable different in performance?

3.) Does the issue persist if the TUSB212 of a problem board is placed on a confirmed-working board?

Nan Zhang said:

For this issue, the customer want to know why the handshake and transmission of the USB link will return to normal and no error will be reported when the dc boost is reduced;

The device could be exceeding disconnect threshold during the handshake process at higher DC Boost levels, resulting in a failed connection, which a lower DC Boost level does not pass this threshold.

Nan Zhang said:

Q2. Could you please show more details that how the DC boost works?

DC Boost is used to increase the VHigh and VLow levels of the eye diagram, allowing for hopefully larger margins between the top of the measured eye and the eye mask. These eye diagrams are a good example, showing the margin between the mask and the top of the eye increasing as the level increases.

Nan Zhang said:

Q3 Could you please help me review this schematic?

One thing I noticed here is that one of the capacitors is 4.7uF, when our typical application specs that capacitor to be 1uF in the datasheet. Changing that may help prevent issues that could occur during the power-up process.

Please let me know once those eye diagrams can be sent.

Thanks,

Ryan

Hi Ryan,

      Sorry for been late. We finally get eye diagrams.

Notice :

1.Add 10% margin to all test eye diagram templates;

2.When device board is plugged into the host board causing the host board to report the usb error -71 and -110, the device board is called NG board;

3.When device board is plugged into the host board causing the host board  not to report the any error, the device board is called OK board;

yours

nan

Hi Ryan,

     This issue is urgent, Could you please have meeting with customer ?

YOURS

NAN

Hi Nan,

Brian and I will be at the meeting tonight.

Thanks,

Ryan

Hi Nan,

If possible, I would like to capture some eye diagrams with a few changed settings.

For settings on the TUSB212, would it be possible to drop the AC Boost settings down to level 1 and take the eye diagram using two single-ended probes rather than a differential probe?

Currently, with the AC Boost settings set to level 3 and DC Boost set to high, we believe that these settings are causing reflections to appear in the signal, resulting in the signal to exceed the disconnect threshold that is set by the host. By lowering AC Boost down to a lower level, such as level 1, the amount of reflections should decrease and improve the signal quality. 

Please let me know if you have any other questions.

Thanks,

Ryan

Hi Ryan,

     The customer said AC set as 1 and DC as 80mV, the failing board still repots error;

                                     AC set as 1 and DC as 60mV, the failing board recovers; 

Ryan Kitto said:

By lowering AC Boost down to a lower level, such as level 1, the amount of reflections should decrease and improve the signal quality. 

      It did not work.

TUSB212 issue from customer_0713.pptx

YOURS

NAN

Hi Nan, 

Ok, I understand. We will discuss more in the meeting later, but we believe the issue lies mainly in the DC Boost then, as the current boost settings could be over-compensating for the signal loss. Looking at the eye diagrams you sent, the signals seem to be treading very closely to the disconnect-threshold at 60mV while disconnecting at 80mV. Setting the DC Boost of the device to 60mV or even 40mV should resolve the issue.

Thanks,

Ryan