Help with LTSpice Simulation: LTC3350 Application Circuit#5

Thread Starter

lindula

Joined Sep 23, 2016
18
Hello, I am trying to simulate a circuit in LTSpice and am having some troubles. The first problem is when I run the Simulate I get the message at the bottom of the screen, "Pseudo-Transcient Analysis" and it it keeps running. If I hit the ESC button is stop and I am able to put probes in my circuit. What is Pseudo-Transcient Analysis and why does it take forever to run. My last question or problem is that the circuit is not functioning properly. I get 0V at Vout.

I am trying to simulate the Application Circuit #5 of the LTC3350 datasheet. This is a backup power supply using supercaps. Can anyone look over my circuit and maybe see what I am doing wrong? See page 41 of the LTC3350 datasheet.

Thank you very much,
Joe
 

Attachments

Alec_t

Joined Sep 17, 2013
10,367
Tick the 'Skip initial operating point' box to make the sim run faster.
Why is you circuit input high for only 400 uS?
 

Alec_t

Joined Sep 17, 2013
10,367
You have your supercap capacitance set as '10F'. In Spice-land that means 10 femtoFarads ! Try '10' instead.
 

Thread Starter

lindula

Joined Sep 23, 2016
18
Thanks for responding to my post. Can you please tell me where the "Skip initial operating point" is located?

Thanks,
Joe
 

Thread Starter

lindula

Joined Sep 23, 2016
18
The LTC3350 Backup Calculator can be used to determine how long of a backup reserve you can have with various settings. I'm setting the Vout to be 5V with POUT of 16W that should give me about 4 seconds of backup time. I would like to simulate this so my question is will I be able to simulate 10 seconds?

thanks,
Joe
 

Thread Starter

lindula

Joined Sep 23, 2016
18
Hello, I have some progress. Thank you very much for all your help. I am able to get 10V on Vout when Vin is cut. The problem that now I need to work on is that I should be getting 5V on Vout. I'll upload my design and work on it some more tomorrow.
 

Attachments

Top