LM2678 Pspice Simulation

Thread Starter

Bserar79

Joined Oct 24, 2018
12
Hello guys!

Recently i was trying to built myself a homemade SMPS, an i found AfroTech's video on how to build a Buck converter.

So, before shoveling quite an amount of money on the LM2678-ADJ (quite expensive in my country), i said i should try to run some Spice simulations on it. Unfortunately i came across some big problems.

So i got the Spice model from TI's website, put together a symbol for it, built the example circuit from the datasheet, and the simulation will get convergence failure (it will go in DEFCON) after about 18.7us.

Checked the pins and the connections 100 times. Also tried running the simulation with these options:

.option cshunt=1e-15 reltol=0.003 abstol=1e-10 gmin=1e-10
.ic V(n004) 5V
.tran 10ms uic

in every possible combination, yet it did not work.

Here's a picture of the circuit:

1574796178701.png

Note: here i'm trying just a simple transient, but it's the same result with the other options.

Really curios why it's not working. Also tried simulating some TI designs in the past without success, so this one really sparked my interest.

I'll also leave my .lib file and .asy file, maybe is something wrong there.

Thank you for all your help guys. Keep up the good work here. Cheers! :)
 

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Thread Starter

Bserar79

Joined Oct 24, 2018
12
As a side note, i read somewhere on the internet that the Spice model provided, which i posted here, is for the fixed 3.3V version of the converter, that's why used that configuration to run the simulation. Also tried with a the normal adjustable schematic, no luck either.
 

Thread Starter

Bserar79

Joined Oct 24, 2018
12
Thank you very much for the fast, concise and helpful response, mate. That's quite some Spice going on there. Saved me a lot of trouble. Have a great day! :)
 
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