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USB0 interface on the OMAP L138

Louka Taymans
Prodigy 470 points
Other Parts Discussed in Thread: OMAPL138

Hi all,

From my customer  a question popped up concerning the USB0 interface on the OMAP L138 (OMAPL138BZWT4).

It is currently used throughout numerous projects at , as it is a part of their , an in house developed software platform based on the OMAPL138, and they have the following questions:

  • "What are the consequences if the pin USB0_VDDA12 is not connected?"
  • "It is not clear to us what “proper device operation” - as mentioned in the datasheet-  means in this case?"

Thanks in advance,

Kind regards,

Louka

 

 

  • 0
    TI__Guru* 83715 points

    Hi Louka

    We found that the PHY spec recommends 0.22 uF (1 uF was for an older generation of the PHY). We don’t have a quantification of what can be the impact, however we wanted to ensure that customers developing new design, when using USB0 should use a 0.22uF.


    In general, having incorrect capacitance can affect the stability of the LDO. However we have never seen any issue reported by any customer, on any sort  of USB related failures either. 

    If they are not using USB0 , and had it "no connect" as previously recommended in the datasheet, overall I think  should be ok as the USB PHY and clocks are all disabled by default.

    For any new designs we recommend that they make the design changes as recommended in the updated datasheet. 

    Regards

    Mukul