DC/DC converter in LTspice

Discussion in 'General Electronics Chat' started by strantor, Apr 30, 2012.

  1. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    I want to simulate my DC/DC converter in LTspice. it is 12Vin, 1000V out, 1.5W. The way it behaves is that it will output 1000V into a high resistance load, but when the resistance gets below a certain number, the output voltage starts to drop, as the wattage is exceeded. I calculate that the converter should put out 1000V into a 666,666Ω load; anything below that, and the voltage should trail off linearly to zero as resistance goes down to zero (I think).

    I have not been able to figure out how to do this. I input a series resistance of 666,666Ω but that results in serious loading which is not right.

    BTW this is the part.
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,993
    3,229
    What do you mean "serious loading"?

    Post your LTspice simulation and .asc file.
     
  3. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    [​IMG]

    I put in 666,666Ω series resistance into the voltage source and it causes the output voltage to drop to 600V when I introduce a 1MΩ resistor to the circuit. This is the correct thing to happen if the voltage supply really had 600Kohm series resistance but I need it to output 1000V is there is a 1MΩ resistor in the circuit.
     
  4. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    657
    Your description of your DC-DC converter is that of a voltage regulator with current (or power) limiting. You simulation is simply a battery with a series resistor. That is not a voltage regulator.
    Here is a simulation of an ideal 1000V source with 1.5mA current limiting.
     
    strantor likes this.
  5. crutschow

    Expert

    Mar 14, 2008
    12,993
    3,229
    As Ron stated, a fixed resistor in series with a power supply is not the type of current limiter they use in a power supply. It is an active circuit that performs the function of Ron's ideal circuit.
     
    strantor likes this.
  6. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    That's great, works just like I want. Thank you.
     
Loading...