Below is the simulation of PSPWM running Linear Technology's own test fixture of the LTC1922-1 (found in the LTspice Power Products folder).
I'm surprised at the messy state of the output voltage across the load. Is this the best the chip can do? I understood that PSPWM involved zero-voltage switching, supposedly to minimise switching noise.

 

Looks ok to me.

 

hi @eetech00
I get similar to Alec, also note Vout ~+3V compared to your +5V, alec's also lower.?

E

 

hi @eetech00
I get similar to Alec, also note Vout ~+3V compared to your +5V, alec's also lower.?

E
View attachment 257378

Hi E
Not sure what you mean, but...
Judging by the feedback resistor divider, its a 5v output design.

 

Looks like the error Amplifier is unstable. I would have expected another capacitor from comp to feedback.

 

hi eetech,
If you post your working asc file, I will try and see if that makes a difference.

Not sure what you mean, but...
I am pointing out that your sim shows a +5V out whereas mine shows around only ~+3 Vout

E

 

hi eetech,
If you post your working asc file, I will try and see if that makes a difference.

Done

Not sure what you mean, but...
I am pointing out that your sim shows a +5V out whereas mine shows around only ~+3 Vout

E

Sorry, that wasn't clear, I thought you were expecting the output to be 3v.

File is attached. The only thing I changed was the simulation time to match alex_t's.

 

hi @eetech00
Tried got the same result, then checked my Control panel, Trtol set to 7 [ for a previous job] Reset it back to '1' and got the correct simulation result as per yours.
Thanks.
E

 

What was the purpose of setting Trtol to 7 in your previous job?

 

Thanks guys. I've also been using Trtol set to 7, 'cos that often seems to help convergence. I'll bear in mind how fiddling with it can make a big difference.

 

hi Carl,
It was to help convergence, based on the info in this link.
E
http://ltwiki.org/LTspiceHelp/LTspiceHelp/SPICE_.htm