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USB Client not detecting after field usage

Rajeev
Expert 1355 points

Greetings All,

I am using AM335X microprocessor, as per our requirement we have a USB client provided so end user can connect to PC and

download data required for analysis.

Problem is after field deployment of the units, after some days USB Client/Device will not get connected to PC.

If we use other AM335x module in same unit it will work fine.

What would be the problem for failure of USB Client/device.

Following schematic is for your reference. 

Regards,

  • 0
    TI__Guru**** 393215 points
    Hi Rajeev,

    Why have you placed this R20/R21 divider before USB0_VBUS? This pin is 5V tolerant, it should sense the 5V VBUS supply directly from the connector, at most a 1K serial resistor is allowed. I would also suggest you add protection devices on all USB signals if this is to be used in the field.
  • 0 in reply to Biser Gatchev-XID
    Expert 1355 points

    Hi Biser,

    Yes what you said is correct, maximum voltage for USB0_VBUS is 5.25V,  Used R20 & R21 it so to supply 3.3V to USB0_VBUS.
    At 3.3V also it is working fine but after 6 months or so device is not getting detected.
    Is there a problem providing 3.3V.

    For protection PGB001060MR-X protection diode can be used or is there any other part which can handle it.

    Thank you,

  • 0 in reply to Rajeev
    TI__Guru**** 393215 points

    From what I know USBx_VBUS voltage should be above 4.4V for a session to start, unless you override VBUS detection by software. As for the ESD protection, TI has a range of ESD protection devices suitable for USB: http://www.ti.com/lsds/ti/interface/esd-emi-protection-products.page#p158=USB 2.0