Looking for SPICE Model of PNP

[engr_joni_ee]

Hello,

I am wondering how can I add "FMMT591" SPICE Model in LT SPICE Library ? There is no option of create new symbol.

 

[aliarifat794]

Hello, does not the method mentioned here work in your case? https://www.analog.com/en/resources...imple-steps-to-import-third-party-models.html

 

[engr_joni_ee]

I already know this procedure. The problem is that there is no option of Create Symbol. I have attached a screenshot in the first post.

 

[stenzer]

Hi,

your model is a ".MODEL" whic is intended do be used with an intrinsic Spice device, see here and also this video.

BR

 

[engr_joni_ee]

I just manage to include the SPICE Model. I am not sure if it is working fine or not.

In PNP transistor, to turn on the transistor, the base voltage has to be below -0.6 V. Such that emitter to base is +0.6 V forward bias. But in simulation it is not like that. It seems to be conducting.

When the transistor is not conducting (base voltage is higher then -0.6 V) the collector voltage should be the supply voltage.

 

[stenzer]

Hi,

you have only changed the reference designator from "Q1" to FMMT591. You have to change the "value" PNP to FMMT591, see my attached image in the previous reply.

BR

 

[engr_joni_ee]

I have changed the value to "FMMT591". I am not sure about Prefix. It is QP. Kindly have a look at the simulation and let me know if I need to change anything more.

 

[stenzer]

Decrease the increments in your DC analysis from 10 (at the moment: .dc Vin 0 -3.3 10) to e.g. 0.01. That's your voltage step/increment. At the moment you only cover "1" step, as your voltage span of interest is only from 0V to -3.3V.

BR

 

[engr_joni_ee]

I thought it as number of steps. But now I understand that it is one voltage step/increment. I will change it and run the simulation again. Thanks you notice.

 

[engr_joni_ee]

I have changed the supply to -5V then it start working.

I am still wondering about Prefix. It is QP. Do we have a list of Prefix for different devices ?

 

[FvM]

BJT prefix is Q, npn or pnp is decided by model. It's generic SPICE syntax, you can refer to LTspice help

Q. Bipolar Transistor

Symbol Names: NPN, PNP, NPN2, PNP2

Syntax: Qxxx Collector Base Emitter [Substrate Node] model [area] [off] [IC=<Vbe, Vce>] [temp=<T>]

Example:

Q1 C B E MyNPNmodel.model MyNPNmodel NPN(Bf=75)

Bipolar transistors require a model card to specify its characteristics. The model card keywords NPN and PNP indicate the polarity of the transistor.