TINA/Spice/TLC551: Resolve NP and NZ parameters using correct VT definition.

Pongo

Part Number: TLC551
Other Parts Discussed in Thread: TINA-TI,

Tool/software: TINA-TI or Spice Models

Hello,

I'm attempting to use your tlc551 spice model in LTSPICE, and am getting errors stating: "Can't resolve .PARAM NP = {0.3/(VT*LOG(1 + 5.0M/ISP))}" and "Can't resolve .PARAM NZ = {0.3/(VT*LOG(1 + 5.0M/ISZ))}". The issue appears to be the parameter "VT", which is not defined anywhere in the code, but is used.

I can get the simulation to run, but it requires me to include the statement, ".PARAM Vt={any number}" before any definition of NP or NZ. I don't know what "Vt" is supposed to do so I have no idea what the effect is, but it can't be good.

Is there a way to get the simulation to run without arbitrarily fixing Vt? What does Vt represent?

Thanks

over 7 years ago

0 Ashis Mondal over 7 years ago

TI__Prodigy 610 points

Hi Pongo,

Here, Vt represents Thermal Voltage = kT/q = 25mV at 20 degree C;
where k=Boltzman's Constant, T=Diode Temperature in degree Kelvin,q=charge on an electron in coulombs.
You can simulate the model keeping Vt as 25mV.

Best Regards,
Ashis

0 Pongo over 7 years ago in reply to Ashis Mondal

Intellectual 270 points

Thanks Ashis,

Do you have any ideas why this parameter was not defined anywhere in the code? I'm trying to understand what might have caused this so that I can troubleshoot the rest of the code for similar issues if there are any.

0 Ashis Mondal over 7 years ago in reply to Pongo

TI__Prodigy 610 points

Hi Pongo,

PSpice Simulator takes Vt as 25mV by default.

Best Regards,
Ashis

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TINA/Spice/TLC551: Resolve NP and NZ parameters using correct VT definition.