Dear Sir/Madam,

I am new to working with LTSpice and after watching the tutorials and many videos I tried to simulate the LTC3109 typical application from the datasheet and I am not getting the desired input nor output.
I have attached the Datasheet as well as the schematic.
The circuit to be simulated is in the datasheet page 19(1st circuit).
the coupling of the inductors is done through the SPICE directive option.
And the from one of the threads I found that the inductor value ratio is directly proportional to square of the turns ratio, that is why 1:100 turns ratio is converted to 1u :10000u value.
instead of the thermoelectric generator model(which i did not find in LTSpice), which generates a 30mV , I have used a 30mV DC input.

The requirement is to get 3.3V as output from a 30mV input.

 

Hi

Right click on the LTC3109 symbol and choose "Open this macromodel test fixture".
You can then run the simulation using Linear Technologies test fixture.

 

Thank you Sir, but I have already done that and used the same macromodel as the base and then added the components as per the circuit from the datasheet.

 

Hello All,

As per my previous post, the issue is not solved yet. And during my findings, I came across a similar circuit which just to confirm I wanted to simulate and verify as LTC3108 also is related to energy harvesting
.
I have attached two schematics.
1) LTC3108_TA02(reference ckt simulation)
2) LTC3108_TA02 replica

I found the 2) circuit from the LTC website and I tried to simulate it and it worked.
I then tried to replicate it 1) and simulate and I do not get the desired input and output.

Could you please tell me where is the mistake or what is that I am missing on.

 

Try this mod of your circuit :

 

@Alec_t
Thank you for the model, I simulated it and it took approximately 4 hours to complete the simulation. Vout was not exactly 3.3V but it definitely gave an idea and I increased the simulation time to 18s and then I got the 3.3v output. I am wondering how is it possible that the circuit from the datasheet did not work and had to be corrected to get the output. Is there a valid justification for this? I am very curious to know.
As a beginner like me, circuits in the datasheet is everything and after you suggested a modified circuit which led towards the required output, I am very confused.
Could you provide the details as it would really help me understand the basics behind the approach and help me in future designs..
Also, is there any way I can speed up the simulation process and I am hoping that this is just the case in simulation and not in practical scenario.
is that right sir?
I will utilize this approach in the next model and let you know the results.

Try this mod of your circuit :

 

Also, is there any way I can speed up the simulation process

If you reduce the value of the output capacitors it should speed up the simulation.

 

Could you provide the details as it would really help me understand the basics behind the approach

The modification was just a 'suck it and see' approach based on symmetrical use of the A and B sections of the chip.

 

hello mam/sir,
I would like to ask on how to open the file with he extension name .asc
I keep on downloading it but i cant open it. Please help me . thank you

 

Hello All,

As per my previous post, the issue is not solved yet. And during my findings, I came across a similar circuit which just to confirm I wanted to simulate and verify as LTC3108 also is related to energy harvesting
.
I have attached two schematics.
1) LTC3108_TA02(reference ckt simulation)
2) LTC3108_TA02 replica

I found the 2) circuit from the LTC website and I tried to simulate it and it worked.
I then tried to replicate it 1) and simulate and I do not get the desired input and output.

Could you please tell me where is the mistake or what is that I am missing on.

 

hello sir where can I open your attached file ?

 

hello sir where can I open your attached file ?

Just save it and open it with LT Spice. It worked for me. I was actually able to load it direct into LT Spice when I download it. It is taking a very long time to run.

 

hello mam/sir,
I would like to ask on how to open the file with he extension name .asc
I keep on downloading it but i cant open it. Please help me . thank you

Once you download the file, right click on the file and open it using LTSpice.

 

You need to get a free download of LTspice here:
http://www.linear.com/designtools/software/#LTspice

 

hi Arshad,
can you please share the circuit in which you got output within short period.
i will very thankfull for your help.

@Alec_t
Thank you for the model, I simulated it and it took approximately 4 hours to complete the simulation. Vout was not exactly 3.3V but it definitely gave an idea and I increased the simulation time to 18s and then I got the 3.3v output. I am wondering how is it possible that the circuit from the datasheet did not work and had to be corrected to get the output. Is there a valid justification for this? I am very curious to know.
As a beginner like me, circuits in the datasheet is everything and after you suggested a modified circuit which led towards the required output, I am very confused.
Could you provide the details as it would really help me understand the basics behind the approach and help me in future designs..
Also, is there any way I can speed up the simulation process and I am hoping that this is just the case in simulation and not in practical scenario.
is that right sir?
I will utilize this approach in the next model and let you know the results.