TUSB4020BI: TUSB4020BI can identify only one downstream devices

Paul Ren

Prodigy 640 points

Part Number: TUSB4020BI

Hello,

My customer is using TUSB4020. Somehow, the devices can identify only one downstream device occasionally.

After reset the system, TUSB4020 go back to normal operation and can identify two channel devices.

This problem will occur with low probability. Power up sequence complies datasheet requirement.

Could you help suggest any other possible reason?

Thanks!

Paul

over 5 years ago

0 Malik Barton57 over 5 years ago

TI__Guru 64326 points

Hi Paul,

Could you give more details on when the system does not recognize the device? Does this happen with multiple devices? When the device is not recognized what is the state of the crystal clock?

0 Paul Ren over 5 years ago in reply to Malik Barton57

TI__Prodigy 640 points

Hi Malik,

This problem occurs when there are two devices connected downstream and always goes with port 2.

During this problem, the clock work normally.

Could you suggest details we need check?

Thanks!

Paul

0 Malik Barton57 over 5 years ago in reply to Paul Ren

TI__Guru 64326 points

Hi Paul,

Does this happen with multiple devices? Can the customer use the USBView application or Probe DP/DM in the failure case? We should confirm whether the device is enumerating over USB 2? Is there a schematic that I can review?

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TUSB4020BI: TUSB4020BI can identify only one downstream devices