Problems with my first SPICE model

[James_A]

Hi everyone

I’m trying to create a spice model for a MC34063switching regulator. I’ve used a pspice model from the on-semi web site tocreate the component model, but I can’t make it simulate correctly.

The spice file seems to contain models forboth the MC34063 and MC34063A. I’m guessing that by mapping my symbol pins tonodes 1-8 that my model should be a MC34063A.

I’ve attached my test circuit.

If anyone can tell me where I’m going wrongI’d greatly appreciate it.

Thanks,

James 

[Mark M]

Hi James,

Did you build your test circuit from a AN or yourself? Do you have a reference of the correct way this circuit should be working?

Also, which SPICE model did you download from on-semi website? I can see there are a couple of them, and they are all for MC34063A. Do you understand the difference between MC34063 and MC34063A? I am guessing in terms of the opeartion they are inherently the same.

[Humanityrulz]

Hi,

      I gone through AN920-D , steup/douwn switching regulator operation for my application(PAGE-17), in that Co value calculations, I didn't get it.

In that application Co=15.7uF you got, but by considering the ESR , considered Co=330uF with ESR=0.12ohms, but I tried to satisfy these values in ESR equation(PAGE-19), I am getting -ve ESR value, for Co=330uF and also  Itried with ESR=.12ohms, Co is not matched with 330uF.

Where it is gone wrong? my calculations or equation or parameter considerations?

Can any one clarify this please.

In my applications most of the time Co is  failing ?

Can any one give me some suggestions in this plaese... thank you in advance...:manhappy: