hi I want to put the value that I calculate with meas function. I have problem. I adding error pic.How can I fix it?

thanks in advance

 

The error says something about R1 but you do not show R1 on the schematic.
Your R3 has no resistance.

 

hi p2p,
Please post your complete circuit and asc file.
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I adding asc file

 

params are evaluated statically before the simulation runs, therefore you cannot assign a value calculated during/after the run and all ".meas" fail.

If you explain exactly what you're trying to achieve we can,maybe, suggest an alternate strategy





Since R1 not connected to anything I(R1) will always be 0

Also Vout- is redundant as its assigned automatically to GND.

 

I want to assign the calculated rin value to R2

 

hi p2p,
As @Irving explained, in order to calculate using .meas, LTS needs the Rin Value to start the calculations.

You have an error in a param command, it needs V(VIN+)
.meas VinRMS RMS V(VIN+)

LTS error message:
WARNING: Can't resolve .param r=rin
Questionable use of curly braces in "r2 vin+ 0 {r}"
Error: yet unevaluated parameter in: "[r]"
Circuit: * C:\Users\ericg\Desktop\simplified dc-dc.asc

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hi p2p,
Run this modified version as a quick test of the circuit.
Read the LTS Error log.
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I don't want this, I want it to replace the value I calculated, is there any other way?

 

Can you explain why you want R2 to vary with the output power?

 

I will make a frequency-independent DC/DC converter that I will use in my homework. I calculated the efficiency of the module I will use according to the current I will draw. I will make this circuit subcircuit and enter 4 external parameters. IN_MAX IN_MIN VOUT EFFICIENCY

 

like this
https://www.bee-tech.info/simple-model-for-spice/dcdc-converter-model/

 

hi p2p.
The link does not give the circuit design within the Yellow box area.
I am not paying $90 for the model, do you have a free Copy.?
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@p2p
Have you seen this link?
https://www.analog.com/en/technical...del-for-current-mode-dc-to-dc-converters.html
And this PDF.

 

hi p2p.
The link does not give the circuit design within the Yellow box area.
I am not paying $90 for the model, do you have a free Copy.?
E

@p2p
Have you seen this link?
https://www.analog.com/en/technical...del-for-current-mode-dc-to-dc-converters.html
And this PDF.

Hi Eric,

Interesting article that shows how to simulate a generic DC/DC converter without having a specific chip model, but it still simulates on a cycle by cycle basis. However, the simulation the TS linked to appears to be a static parameter model that doesn't operate on a cycle by cycle basis but provides a time-averaged approach. It appears, for example, to require a fixed input value for efficiency whereas the cycle by cycle model calculates the efficiency of the conversion at the specified load point.

I think the point of the thread is that the TS doesn't want to pay $90 either (seems steep to me too) so is trying to create something similar.

 

I will make a frequency-independent DC/DC converter that I will use in my homework. I calculated the efficiency of the module I will use according to the current I will draw. I will make this circuit subcircuit and enter 4 external parameters. IN_MAX IN_MIN VOUT EFFICIENCY

Given its DC to DC, why are you inputting a sine wave?

 

Does this acheive your requirements?

 

Given its DC to DC, why are you inputting a sine wave?

I was testing max min voltages.

 

hi p2p,
Use this type of Voltage source PWL.
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Better still, use a step function since only min/nominal/max required.