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OPA858 Floating Node on LTSpice

Tam Tran1
Prodigy 10 points
Other Parts Discussed in Thread: OPA858, THS4541

Hi All,

I exported the OPA858 model into LTSpice but when I run a simulation I have the following problem:

ERROR: Node U1:I0:I21:1:102 is floating and connected to current source G:U1:I0:I21:1:RA
ERROR: Node U1:I0:I19:1:102 is floating and connected to current source G:U1:I0:I19:1:RA
ERROR: Node U1:I0:I19:1:302 is floating and connected to current source G:U1:I0:I19:1:RC

u1:i0:vprobe1: Missing value, assumed 0V @ DC
u1:i0:vprobe2: Missing value, assumed 0V @ DC

I am aware that a similar issue has been brought up on the THS4541 here : https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/844373/ths4541-the-pspice-model-for-ths4541-dose-not-work

but I do not know where to add these high impedance resistors.

If I can get anyone to help me and/or lead me in some direction on what to edit on the opa858.cir file that would be great!

Thank You.

  • 0
    TI__Genius 14156 points

    Hi Tam Tran1,

    I see these warning messages also, but the simulation still runs and gives accurate transient results for non-inverting gain.

    Also, I can't find any nodes in the OPA858 model's netlist that match the descriptions given in the warning message.

    Is there a specific simulation result that you are seeing which you believe to be erroneous? Otherwise I would just ignore these warnings.

    Best regards,

    Sean