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[C5535] Unused USB_LDO

Kaka
Guru 24520 points

Hi community member,

Please let me confirm the following question.

[Question]

When customer did not use the USB_LDO, is it no problem that  the DSP_LDOO pin will be "OPEN" state?

If no, would you please show us how should they handle this pin in case of not using DSP_LDO?

[Background]

The USB_LDOO pin is Hi-Z status in disabled the USB_LDO. Now customer think that their system will supply the USB 1.3V domains by external LDO. i.e. They will not use the USB_LDOO.  So, they think that the USB_LDOO pin will connect to this external LDO(1.3V). Do you think that there is any problem for this solution?

If you have any questions, please let me know.

Best regards.

Kaka

  • 0
    TI__Genius 12575 points

    Hi Kaka-san,

    "When customer did not use the USB_LDO, is it no problem that  the DSP_LDOO pin will be "OPEN" state?" .

    VK: I could not understand your question completely - Could you please clarify on DSP LDO in your question.

    [Background] The USB_LDOO pin is Hi-Z status in disabled the USB_LDO. Now customer think that their system will supply the USB 1.3V domains by external LDO. i.e. They will not use the USB_LDOO.  So, they think that the USB_LDOO pin will connect to this external LDO(1.3V). Do you think that there is any problem for this solution?

    VK: can you let me know why you want to connect USB_LDOO pin to external LDO ?  Please refer to schematic checklist for details on how to handle unused pins/LDOs.

    processors.wiki.ti.com/.../35_Schematic_Checklist.

    " If an on-chip LDO output is not used

      • If an LDO is not used, leave the LDOO output pin floating "

    Regards

     Vasanth

  • 0 in reply to Vasantha K
    Guru 24520 points
    Hi Vasanth,

    I apologized for some confusion. I had a mistake in my post.

    >"When customer did not use the USB_LDO, is it no problem that the DSP_LDOO pin will be "OPEN" state?" .
    >VK: I could not understand your question completely - Could you please clarify on DSP LDO in your questio
    [Kaka]
    I had a typo in this question.
    When customer did not use the USB_LDO, is it no problem that the USB_LDOO pin will be "OPEN" state?
    So, I think that it is OK. Right?

    >VK: can you let me know why you want to connect USB_LDOO pin to external LDO ? Please refer to schematic checklist for details on how to handle unused pins/LDOs.
    [Kaka]
    I do not understand why customer would like to connect this pin to external LDO. So, I will inform them that not connect it and why they would like to do.

    Best regards.
    Kaka
  • 0 in reply to Kaka
    TI__Genius 12575 points

    Hi Kaka-san,

    Below is my response.

    [Kaka]  I had a typo in this question.
    When customer did not use the USB_LDO, is it no problem that the USB_LDOO pin will be "OPEN" state?
    So, I think that it is OK. Right?

    VK:  Yes that's right.

    [Kaka]
    I do not understand why customer would like to connect this pin to external LDO. So, I will inform them that not connect it and why they would like to do.

    VK. Yes.

    Hope this clarifies.

    Regards

     Vasanth

  • 0 in reply to Vasantha K
    Guru 24520 points
    Hi Vasanth,

    Thank you for your confirming.
    I　understand them.

    Best regards.
    Kaka