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Original question:

LM5118: LM5118MH/NOPB line regulation issue; I/P: 9V-36V , O/P: 28V Current: 1A

LM5118: Simulation Error while Simulating LM5118 unencrypted model in Simetrix 8.3

ATHIESHKUMAR T
Intellectual 390 points
Part Number: LM5118

Hi , 

    I am using LM5118 for realizing Buck-boost Converter. The design is such that the Input Voltage (6V-26V) to Output Voltage (15.5V) with full load current of 2.25A. I am simulating the same in Simetrix using LM5118 unencrypted model, but it shows the following error. 

There are errors in the circuit. Simulation aborted

design.net (107): Ren2gnd EN GND 1/gmin

*** ERROR *** Cannot evaluate '1/gmin'

Need help regarding this.

Thanks & Regards

Athieshkumar T

  • 0
    TI__Mastermind 21720 points

    Hello Athieshkumar,

    Thanks for reaching out with your questions.

    Did you try connecting the EN pin directly to the input voltage? It looks like this is throwing an error about the resistance to ground on the enable pin.

    Thanks,

    Garret

  • 0 in reply to Garrett Roecker
    Intellectual 390 points

    Hi Garret, 

         I tried the option you have mentioned, but the error still persists. Can anyone update the spice model that should work with Simetrix

    Also I tried replacing 1/gmin with 1E12 in the spice code. But a new error occurred which is shown below.  


    Errors found during the run. Simulation aborted

    *** ERROR *** Model 'U5._S16_mod':VH must not equal zero
    *** ERROR *** Model 'U5._S15_mod':VH must not equal zero

    This is because of the spice model (part of it) shown below:

    .MODEL _S15_mod vswitch VT=0 VH=0 RON=30

    Ccs EmulatedIL RAMP 2nF

    SRamp RAMP GND SRampctl GND _S16_mod

    .MODEL _S16_mod vswitch VT=0 VH=0 RON=100

    Thanks & Regards

    Athieshkumar T

  • 0 in reply to ATHIESHKUMAR T
    TI__Mastermind 21720 points

    Hi Athieshkumar,

    We don't directly support models other than the SPICE model, and I am not all that familiar with Simetrix.

    Did you try opening the LM5118 sub-circuit? Maybe that will help to debug the issue.

    Thanks,

    Garrett