TUSB4020BI: USB test state-J stake-K

user5547842

Prodigy 80 points

Part Number: TUSB4020BI

when I start the USB test mode state-J/K it will be automatically reset after about 1sec.

but it should be continuous activated

what could be the reason for it ?

over 7 years ago

0 David (ASIC) Liu over 7 years ago

TI__Guru**** 183531 points

Are you using high speed test fixture for the test? Once Test_J and Test_K commands have been sent, are you terminating the USB signal with 45ohm to GND?

Thanks
David

0 user5547842 over 7 years ago in reply to David (ASIC) Liu

Prodigy 80 points

Yes I use the test fixture. But it is only a mechanical board to connect an oscilloscope.

When I connect the data lines to a resistor of 45ohm I see the J/K signals with half level. So the output resistance of TUSB4020 is about 45ohm.

But after 1 second the test signal is automatically terminated. So I have only 1 sec for measurement.

0 David (ASIC) Liu over 7 years ago in reply to user5547842

TI__Guru**** 183531 points

Are you following the USB compliance test procedure as outlined on the USB.org and use HSETT tool for the compliance test? .

0 user5547842 over 7 years ago in reply to David (ASIC) Liu

Prodigy 80 points

I use our own test tool. But I managed to do the electrical measurements within 1 sec. so it is ok for now.
I will try HSETT as soon as possible.

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TUSB4020BI: USB test state-J stake-K