duty cycle sweep

I'm doing an LT Spice sim where I want to sweep a duty cycle from 0 to
100% and graph a resulting power supply output, basically kill the
error amp and run open-loop.

I'm doing this, which works but seems klunky. It sweeps 0..100% in 100
milliseconds. There must be a more elegant way.

https://www.dropbox.com/s/whnz4bsp8v2e9do/Duty_Cycle_Sweep_1.jpg?raw=1

To be fair, it's barely dawn on a Saturday morning and I've only
finished half a cup of Peets.





--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

 

jlarkin@highlandsniptechnology.com wrote in
news:bq4b3f1iau7avdq29468ofih8p9jjjvfse@4ax.com:

I'm doing an LT Spice sim where I want to sweep a duty cycle from
0 to 100% and graph a resulting power supply output, basically
kill the error amp and run open-loop.

I'm doing this, which works but seems klunky. It sweeps 0..100% in
100 milliseconds. There must be a more elegant way.

https://www.dropbox.com/s/whnz4bsp8v2e9do/Duty_Cycle_Sweep_1.jpg?ra
w=1

To be fair, it's barely dawn on a Saturday morning and I've only
finished half a cup of Peets.

We used labview and an HP network analyzer to step our phase
shift/attenuators through a 190 degree shifts at a few degrees at a
time, because the vendor (a big player) sent us 800 units that THEIR
QA failed to test correctly... only testing the two extremes and
passing the units. The stepped test showed that some of the units
did not properly go through the phase shift steps. At hundreds of
dollars each with 16 each in a 4U device that had to be nearly fully
disassembled to remove them. how quaint. It set us back months. As
we had 8 of those 4U units in each of 12 full height racks. This was
all for the F-35 stimulator that ended up down at Hughes' monster
anechoic chamber.

You could use that little chip (and video) I posted to make a board
that would apply the step voltages (or whatever) to your circuit so
you couldcapture it on your scope at whatever rate you wanted it to
step at.

 

On Sat, 1 Feb 2020 08:54:34 -0800 (PST), Klaus Kragelund
<klauskvik@hotmail.com> wrote:

>https://electronics.stackexchange.com/questions/332057/how-can-i-sweep-duty-cycle-of-a-pulse-train-in-pspice

Maybe I can use scaled {time} (0 to 100 msec of the sim run} as a
parameter of a pulsed voltage source. Somehow.

time is usable as a variable in a BV, but seems to not be general.







--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

 

[Klaus Kragelund]

I normally just do it with a ramp and a comparator like IRL

Then I can add errors that the real component has

Cheers

Klaus

 

[Klaus Kragelund]

https://electronics.stackexchange.com/questions/332057/how-can-i-sweep-duty-cycle-of-a-pulse-train-in-pspice

 

On Sat, 01 Feb 2020 07:35:01 -0800, jlarkin@highlandsniptechnology.com
wrote:

I'm doing an LT Spice sim where I want to sweep a duty cycle from 0 to
100% and graph a resulting power supply output, basically kill the
error amp and run open-loop.

I'm doing this, which works but seems klunky. It sweeps 0..100% in 100
milliseconds. There must be a more elegant way.

https://www.dropbox.com/s/whnz4bsp8v2e9do/Duty_Cycle_Sweep_1.jpg?raw=1

To be fair, it's barely dawn on a Saturday morning and I've only
finished half a cup of Peets.

I'm waking up. This is a little nicer.

https://www.dropbox.com/s/o7mew8afsgpbmu6/Duty_Cycle_Sweep_2.jpg?raw=1

Vosc is a perfect triangle generator. Which has Tr=Tf=0.5/F, and ON
time = 0.

This is part of a very important system that has the dreaded
zero-in-the-right-half-plane thing, which looks like a hazard to me.

https://www.dropbox.com/s/ki97mnnf6i7fbto/Duty_Cycle_Droop_2.jpg?raw=1



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"