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LM5085: The output voltage was 0V with LM5085 transient simulation on PSpice for TI.

Part Number: LM5085

Hello guys,

One of my customers run LM5085 transient simulation on PSpice for TI with the attached circuit.

The simulation was finished normally but the output voltage (C2 voltage) was 0V (the target voltage is 5V).

Do you have any idea or advice why the output was 0V?

Do they need to add any component or so on?

Could you please give me your reply for them?

Best regards,

Kazuya. 


LM5085_tran_schematic.pdf

  • Hi Kazuya,

    Can you tell me the design criteria? (VIN = ?, VOUT = ?, IOUT = ?, FSW = ?) just for to me know what customer application is?

    Also I would suggest starting with the working LM5085 transient model from the product folder and then editing the appropriate components that the customer wants to use.

    From the default setting and component configuration, the simulation results should not take long and look something like below:

    snvm213b.zip

  • Hi Jimmy,

    Thank you very much for your reply. 

    The customer design criteria are the follows.

    Vin=22V, Vout=5V, Fsw=about 350kHz.

    I will ask them Iout and their application later and I will inform you as soon as I get the information.

    As the additional information, the following warning was popped up

    when they opened their simulation schematic I attached the previous asking,

     WARNING(ORCAP-2461): Problems detected with TI model libraries configured in this design. Refer to the session log for details. Some of the libraries are located outside of the design hierarchy and cannot be updated. Update the references to these libraries manually. Refer to Migrating old TI reference designs and libraries under Help -> Documentation for more details.

    Can this problem be solved when they execute your suggestion?

    Thank you again and best regards,

    Kazuya.

  • Hi Kazuya,

    It could be that the TI model circuit is not link correctly in their design simulation file. Again I think starting from the existing PSPICE transient model and appropriately modifying the components of choice would be the best approach here.

    Starting from a known good simulation file will only help make troubleshooting easier if there is anything unexpected.

    As such as a good starting point for simulation, please have the customer use the PSPICE transient model that is available on the product folder.

    Please keep me updated on if the customer has any issues while using the transient model.

    Jimmy

  • Hi Jimmy,

    Thank you for your reply. 

    The customer problem was solved because of your kind supports.

    Could I ask you a few additional questions because they still have the following questions about PSpice for TI?

    Please let me know if I need to ask at a new thread?

    Q1.  Even if it is a TI part, several parts on the selection list has SOP mark.

            Also several part have the mark like network. Is the parts needed to be linked by ourselves

            using  "Configuration Files" → "Library" setting window?

    Q2 . I think a backup folder with date is build to the following directly every part library updating.

           " C:\cds_spb_home\cdssetup\pspTILibDir "

           Can these backup folders be deleted except the newest folder?  

    Thank you again and best regards,

    Kazuya.

  • Hi Kazuya,

    I think you should create a new thread specifically for PSPICE troubleshoot since this is not particularly related to this device.

    Having a new thread mainly for PSPICE issues will allow the appropriate engineer to provide adequate and timely support that will pertain to your general question on PSPICE. Please create a new thread for the two questions you have specifically on PSPICE tool.

    Regards,

    Jimmy

  • Hi Jimmy,

    Thank you very much for your suggestion.
    I will ask those questions on new thread.

    Thank you again and best regards,

    Kazuya.