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ISO7710: ERROR(ORPSIM-15461): Incorrect number of interface nodes

Part Number: ISO7710
Other Parts Discussed in Thread: UCC27536, , PSPICE-FOR-TI

Hello E2E,

Please help our customer wth the error encountered in using our spice models. Here is the full query:

I use ISO7710 and UCC27536 in one design both of them are the product of TI and then once both of them are added to the design (ORCAD) it failed.

"ERROR(ORPSIM-15461): Incorrect number of interface nodes for ISO7710 or ERROR(ORPSIM-15461): Incorrect number of interface nodes for UCC27536"

When I just use one of them in the design, it's ok, it seems that when the Pspice of ISO7710 or the Pspice of UCC27536 works alone, it works well.
It is very strange that when the .lib of ISO7710 takes priority over UCC27536 it's okay. But when I change the order of .lib as seen in the picture, ISO7710 fails and an error appears. Both of the PSpice are downloaded on your website, and I just change the .lib order.

Thank you in advance for the help.

Regards,
Carlo

  • Hi Carlo,

    Sorry to hear about the issue.

    I am not very sure why the ordering of the library files making a difference in the working of models.
    Could you please share the complete schematic when you are using both ISO7710 and UCC27536? I only see ISO7710 in both the schematics you have provided. Thanks.


    Regards,
    Koteshwar Rao

  • Hello Koteshwar,

    Please see the complete schematic below.

    Regards,
    Carlo

  • Hi Carlo,

    Thanks for sharing the schematics and additional information.
    From what I understand, you haven't been able to simulate the two devices together. Based on the ordering of the files, the one that's lower in the order gives an error.

    Please allow me until Friday to investigate this issue with PSPICE-FOR-TI team and come back to you.

    Meanwhile, I noticed that you are driving a MOSFET directly from ISO7710 output. The digital isolators are suitable to be interfaced to TTL/CMOS logic I/Os and are not capable to drive a MOSFET directly. I would recommend you to place the isolator at the input of UCC27536 so that the signal is first isolated and then UCC27536 drives the MOSFET, which is what it is meant for. ISO7710 will have an MCU at input pin end and UCC27536 at its output, both of which are going to be logic I/Os. Thanks.


    Regards,
    Koteshwar Rao