Hello
I know the thread is old, but I have exactly the same issues as dante.
I used the demo simulation from Linear Technologies with LTC3108 which works quite well. But they use a directive which let the Vout start at 3.3V / 2.9V. As well the voltage source which replaces the TEG has 0 Ohm resistance, which does not happen in reality.
When I insert a resistor with 2.8 Ohms and change the voltage to 50 mV it does not work at all. The output voltage stays 0.
How should the circuit work in real, when it does not even fulfill the requirements specified in the datasheet?
And the LTC3108 is specified starting from 20mV, but which inner resistance does the TEG need to have?
Im not sure if I missunderstood anything or did something wrong or the simulation is supposed to work like this.

Thanks

MOD: Created your own new Thread.E

 

Looks like the internal oscillator in the IC needs a bit of a kick start for the sim; hence the .ic command in your posted .asc. Alternatively you can just use a pulse source for Vteg and give it a pulse rise time <100us.
The circuit does seem to need a very low impedance input source. I got the sim to run with 1Ω and Vteg = 25mV. Anything less than 25mV didn't work for me.

 

Looks like the internal oscillator in the IC needs a bit of a kick start for the sim; hence the .ic command in your posted .asc. Alternatively you can just use a pulse source for Vteg and give it a pulse rise time <100us.
The circuit does seem to need a very low impedance input source. I got the sim to run with 1Ω and Vteg = 25mV. Anything less than 25mV didn't work for me.

Thank you Alec_t for your response. Interestengly 25mV / 1Ohm does not work for me as well. The LTC3108 is specified for input ranges starting from 2 Ohm to around 6 Ohms. After using the kickstart to 3.3 V the voltage drops linearly after a couple of minutes, that means there is too less energy in the input. I don't know what I'm doing wrong.

What I am most confused about is, that even the requirements and the recommendations are taken from the datasheet from LTC3108 the simulation does not work. How should it work in real life?

 

What I am most confused about is, that even the requirements and the recommendations are taken from the datasheet from LTC3108 the simulation does not work.

Perhaps there's an error in the datasheet, or in the IC model? It's not unknown .

 

Perhaps there's an error in the datasheet, or in the IC model? It's not unknown .

Thank you for your help!