[SOLVED] Why doesn't this simple circuit work in simulation?

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AlienCircuits

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I expect the switch to turn on and conduct when Vgs = 15V, which is the pulse I'm sending to the gate. However, the switch seems to always be off.


 

Hi Alien
At first why 100 k ohms in drain ? it is too high for switching applications ! decrease it as 1 k ohms or 560 ohms . how much is frequency of your pulses ?
Best Wishes
Goldsmith
 

Hi Alien
At first why 100 k ohms in drain ? it is too high for switching applications ! decrease it as 1 k ohms or 560 ohms . how much is frequency of your pulses ?
Best Wishes
Goldsmith

The 100k ohms is because the supply voltage is 1000V and the MOSFET is only rated for .2A.

The frequency is 50Hz.

I tried your suggestions, changing the resistor to 560 Ohm, and I get the same simulation plot. So it still does not switch.
 

Tell me your frequency , thus i can simulate it , perhaps i could earn success !
 

My pulses are 50Hz.

Here is the model:
 

I have simulated it with another mosfet and 500 volts ! see below , please : ( i think you didn't measure voltage of drain ! perhaps you have putted the probe on VDC ?)

Good luck
Goldsmith
 
I have simulated it with another mosfet and 500 volts ! see below , please : ( i think you didn't measure voltage of drain ! perhaps you have putted the probe on VDC ?)

Good luck
Goldsmith

No, I have measured the voltage at the drain. The netname shows up in my first circuit picture, and that is the name in the simulation plot too. Your simulation shows what I expected to see with my circuit, but my circuit doesn't do this :/

Perhaps my MOSFET model is incorrect? I had to request it in email from the manufacturer.
 

It is a defective Spice model. Edit the first line of the model to be

.SUBCKT IXTP02N120P D G S

then it works.

Keith.
 
I figured out the problem! Thanks goldsmith, you helped me because I am not confident with MOSFETs yet and I wasn't sure if what I saw was incorrect. You verified my thoughts, and so I checked the model.
They created the model non-standard, with the Drain and Gate order swapped. I fixed it and it simulations correctly.

Thank you.

- - - Updated - - -

It is a defective Spice model. Edit the first line of the model to be

.SUBCKT IXTP02N120P D G S

then it works.

Keith.

Hehe, I just found that out and came here to read this
 

You did well to find it. Fixing companies cr@ppy models is not easy. You always assume they have tested them and that you are making a mistake!

Keith.
 

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