Boost Converter Simulation With LT1242 or LT246 PWM Controller

1246_Boost.asc

Hi, my name is Nebi. I am a hardware design engineer. I am working on a boost converter. My converter parameter is as follows.

Vin_min=20 VDC, Vin_max=31 VDC, Vout=75 VDC, Pout=2500 W and frequency=150kHz

I made simulations with LT1242 and LT1246 PWM Controllers in LtSpice. But I have some questions.

The simulation circuit and waveform graph are as follows. In the LT1246 simulation, the Mosfet PWM signal is intermittent. Something is resetting. I changed sense resistor but did not solve this problem. What could be causing this situation?

     

I set up the same circuit for LT1242. A similar reset situation happened here. If sense resistor value is not correct, how can I calculate this resistor value?

    

In addition, I did not find LTpowerCAD model for LT1242 and LT1246. Therefore I could not loop compensation. How can you help with this? Could it be that the output voltage is incorrect because my compensation values are wrong?

Thanks for be interest.

Have a nice day!

Parents
  • HI Nebi,

    I received a response from the apps engineering team. Base on their assessment, this is not a spice issue either, which was what I thought at first but rather, the 2500W load is just too much for this model. A typical application in datasheet on a offline supply application is only at 30W and LT1242 is not designed to drive large FET or parallel FET to support large current.

    You may what to try looking for the suitable part for your design. Please also note to always check the datasheet for its operating region as each models are only designed to operate with the boundary of its specification.

    Regards,

    PaulDaria

Reply
  • HI Nebi,

    I received a response from the apps engineering team. Base on their assessment, this is not a spice issue either, which was what I thought at first but rather, the 2500W load is just too much for this model. A typical application in datasheet on a offline supply application is only at 30W and LT1242 is not designed to drive large FET or parallel FET to support large current.

    You may what to try looking for the suitable part for your design. Please also note to always check the datasheet for its operating region as each models are only designed to operate with the boundary of its specification.

    Regards,

    PaulDaria

Children