MicroCap 12: Problem simulating imported PSpice model (LM3886)

[Aniol1349]

Hello,

I'm new to uCap12 (and simulation in general) and I'm trying to import and simulate a PSpice (.lib) model file which I downloaded directly from TI.
I have copied to .lib file to the main LIBRARY folder and then used "Add Part Wizard" tool to import the model, I selected the 6 pin op-amp model and renamed the pins as they appear in the model file (.SUBCKT lm3886 Vip Vin VDD VSS Vout MUTE)

I constructed a simple circuit and wanted to run the simulation but when I do that uCap shows me the lm3886.lib file and highlights a diode model:

".SUBCKT IDEAL_DIODE_0 A C
+PARAMS: EMCO = 0.01 BRKV = 60 IBRKV = 1M)"

I assume the lm3886 model is relying on another uCap native diode model to work, and that is missing?

Any ideas of how to get it to work would be much appreciated.

Thanks!

[SiliconWizard]

Took a look at the Spice model, and can confirm the line you quoted. The whole diode subcircuit is like so:

.SUBCKT IDEAL_DIODE_0  A C
+PARAMS: EMCO = 0.01 BRKV = 60 IBRKV = 1M)
D1 A C IDIODE
.MODEL IDIODE D(N = {EMCO} BV = {BRKV} IBV = {IBRKV})
.ENDS

Seems to me that there is a typo in the 'PARAMS' list. The final closing parenthesis looks bogus. "... IBRKV = 1M)"
Remove this parenthesis, save the model and try again.

[Aniol1349]

Thanks SiliconWizard,

I will try that this eve and let you know if it worked,
out of curiosity - did you try running the model in uCap yourself?

Regards

[SiliconWizard]

I will try that this eve and let you know if it worked,
out of curiosity - did you try running the model in uCap yourself?

I didn't - but I might try that later if the above fix doesn't solve your problem.

[Aniol1349]

Thanks @SiliconWizard

Your suggestion solved the initial error but now I'm getting this:

microcap 12 failed to converge during ac function source iterations
During a transient DC operating point, or the operating point calculation prior to an AC analysis, or during a DC analysis, if the number of iterations required to solve the network equations exceed the specified maximum, this message is issued.

I also tried in LTspice and initially got the diode issue, applied your suggestion and then got this:

ERROR: Node U1:11 is floating and connected to current source G:U1:U2:R1
ERROR: Node U1:U_TF:VP1 is floating and connected to current source G:U1:U_TF:P1
ERROR: Node U1:U_TF:VP2 is floating and connected to current source G:U1:U_TF:P2
ERROR: Node U1:U_TF:VP3 is floating and connected to current source G:U1:U_TF:P3
ERROR: Node U1:U_TF:VP4 is floating and connected to current source G:U1:U_TF:P4
ERROR: Node U1:U_TF:VZ1 is floating and connected to current source G:U1:U_TF:Z1
ERROR: Node U1:U_TF:VZ2 is floating and connected to current source G:U1:U_TF:Z2
ERROR: Node U1:U_TF:VZ3 is floating and connected to current source G:U1:U_TF:Z3
ERROR: Node U1:U_TF:VZ4 is floating and connected to current source G:U1:U_TF:Z4
ERROR: Node U1:17 is floating and connected to current source G:U1:U_TF:Z5
 
Direct Newton iteration failed to find .op point.  (Use ".option noopiter" to skip.)
Starting Gmin stepping
Increasing initial diagonal Gmin to 100


Test circuit as per TI's application note (single LM3886 in non-inverting config.)

[SiliconWizard]

Could you post your MC12 file (.cir), so I can have a look with your exact circuit?

Note that judging from a few posts here and there about this LM3886 model, it seems pretty simplifed anyway, and for instance relatively useless for simulating noise or distortion in a realistic way. So depending on what you want to simulate, this may not provide much insight.