TS3USB221: jitter in eye diagram

Wiky Liao

Intellectual 1940 points

Part Number: TS3USB221
Other Parts Discussed in Thread: TUSB211

Hi Team,

We find TS3USB221 have some jitter when eye diagram testing, see below test scope and schematic, could you help to share any possible reason for it? thanks.

Best Regards.

Wiky

over 6 years ago

0 Malik Barton57 over 6 years ago

TI__Guru 64326 points

Hi Wiky,

Are you asking about TUSB211 or TS3USB221? TUSB211 is listed in the schematic provided. Could you describe the test case that produced the eye above?

0 Brian Zhou over 6 years ago in reply to Malik Barton57

TI__Guru*** 146055 points

Wiky:
still need help?

0 Wiky Liao over 6 years ago in reply to Brian Zhou

TI__Intellectual 1940 points

Hi Brian and Malik,

Sorry for my typo error, it should be TUSB211.

when TUSB211 doesn't work, there is no jitter, see below scope. The jitter will exist when TUSB211 working. is it normal?

Test flow:

1.connect all the cable

2.Power on the DUT

3.start to test

4.sometimes the OSC couldn’t catch the signal， power off the DUT，and then reconnect the cable between the OSC & test jig, and restart

Best Regards.

Wiky

0 Malik Barton57 over 6 years ago in reply to Wiky Liao

TI__Guru 64326 points

Hi Wiky,

For USB HS compliance testing use the steps listed in section 5.2 USB 2.0 Upstream Signal Quality Testing in the app note linked below. This the best way to test the system. These delayed transitions are not normal, Even in the disable state you can see some separation edges. Is there a common mode choke anywhere is the system while testing?

www.ti.com/.../slla392.pdf

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TS3USB221: jitter in eye diagram