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LM5116: LM5116

Soumya
Prodigy 655 points
Part Number: LM5116
Other Parts Discussed in Thread: LM5145, , LM5164

Tool/software:

Hi,

One of my customers has the following question. 

The TI parts that I am using are LM5116, LM5145 and LM5162. Attached is the schematics for the supplies that we are using. The designs have been taken from what was generated by webench. 

My design requires a couple negative voltage rails.  The designs have been based on Webench designs.  One thing that I am unclear with these designs is how the UVLO and EN pins operate without a ground reference or rather now that ground is now relative to a logic signal that is. Do these logic signals effectively need to be made floating to work?  I presume the PGOOD would also need to be clamped to ground, otherwise it may be pulled below system ground.I have attached our schematics on these for review/commentary.  The -30V supply has enable circuitry that I believe will work, the -15V supply I have not corrected yet as I await your commentary. 

 20250819 - +_-15_+_-30V Supplies.pdf

  • 0
    TI__Guru 58461 points

    Hello Soumya 

    EN input is already level-shifted using this circuit. It looks okay. Please make it sure that '-30V_ANA_ISO_EN' is open-drain/open-collector output 

    . 

    LM5116 doesn't provide PGOOD.

    LM5164's PGOOD is protected by Zener diode now when the PGOOD pin is floating. This circuit needs a current limit resistor when PGOOD pin is connected to -15V_ANA_ISO  

    To see more examples, please refer https://www.ti.com/lit/an/slva540/slva540.pdf 

    -EL

  • 0 in reply to EricLee
    TI__Prodigy 655 points

    Thanks for your quick response and support Eric. I will relay this back to the customer and get back to you with any further questions.

  • 0 in reply to Soumya
    TI__Guru 58461 points

    Thanks for promoting SR-WVB devices. Please feel free to contact me if you have any questions.
    -EL

  • 0 in reply to EricLee
    TI__Prodigy 655 points

    Response from the customer-

    Thank you for the review on these signals.  I will implement the feedback you suggested.   Are you able to provide review for the rest of the PSU implementations?

  • 0 in reply to Soumya
    TI__Guru 58461 points

    Sorry I am in charge of only LM5116. 

    -EL

  • 0 in reply to EricLee
    TI__Prodigy 655 points

    Hi Eric,

    I replied back to the customer that we can only review the LM devices implementation and they asked who can review the rest of the PSU implementation on their schematic. Any guidance?

    They also said that they have received good support from TI in the past with Sch reviews of their part implementations and appreciate the support.

  • 0 in reply to Soumya
    TI__Prodigy 655 points

    Just as an FYI, this customer does not have local FAE support. They are a design house and their end customer does not have dedicated sales support either. I am just trying to help out a TI customer trying to use our parts and would like to get their schematic reviewed. I appreciate you guiding me in the right direction to get this TI customer the support they are looking for. If I need to reach out to someone else to complete the sch review, please let me know and I will do so. 

  • 0 in reply to Soumya
    TI__Guru 58461 points

    Hello Soumya 

    My recommendation is to use email communication. Or you can request the schematic review with different title. 

    -EL