AM335x USB DM/DP short to VBUS

Wolfram Stumpf

Other Parts Discussed in Thread: TS3USB3000

Hi there,

how do I treat the case when DM or DP is shorted to VBUS or GND?

I've seen some devices which are tolerant against these cases but I haven't found anything for the AM335x besides the general statement about VIO -0.6/+0.3 tolerance.

Are there means to protect the data pins against that case externally (besides the common USB TVS devices)?

Regards

Wolfram Stumpf

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

All AM335X I/O pins, except VBUS are not fail-safe. See parameter "Steady state max voltage at all IO pins" in section 5 of the AM335X Datasheet Rev. I. I'm afraid I don't quite understand what is the purpose of this question.

0 -DK- over 9 years ago

TI__Mastermind 27890 points

The Short Circuit Withstand outlined in the USB2.0 specification (section 7.1.1) was deprecated via ECN in 2008 and as such is not supported by AM335x. Please refer to the "5V Short Circuit Withstand Requirement Change" ECN available at www.usb.org.

Please follow the general V/IO tolerances as outlined in the AM335x documentation.

0 Wolfram Stumpf over 9 years ago in reply to Biser Gatchev-XID

Intellectual 445 points

Hi Biser,

I was aware of the steady state max voltage. I was asking for something to protect the Sitara USB pins from shorts to VBUS.

In the meanwhile, I found this:

e2e.ti.com/.../protect-your-application-processors-from-short-circuit-at-9v

which points to the TS3USB3000, a switch for MHL applications.

As I wouldn't have a charger in my application, I would switch between nothing and the Sitara and just take advantage of the protection function of the device.

Might this catch the VBUS short issue? Any other recommendation?

Regards

Wolfram Stumpf

0 Biser Gatchev-XID over 9 years ago in reply to Wolfram Stumpf

TI__Guru**** 393215 points

I'm sorry, we are not line protection experts on this forum. DK gave details of short-circuit performance of AM335X in his post above. For TS3USB3000 I would suggest you ask on: e2e.ti.com/.../388

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AM335x USB DM/DP short to VBUS