• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 2 answers
  • Subscribers 39 subscribers
  • Views 408 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM2842: DC simulation failed

Ben Tay
Prodigy 20 points

Part Number: LM2842

Tool/software:

Hi all, I downloaded the PSPICE transient model of LM2842Y and imported as a new macro.
I then connected it up in the following schematic:

Given the feedback resistors of 28k and 1.5k i am expecting an output voltage of 15V.
However, a DC analysis shows it as 1.95V:

I am pretty new to TINA (just downloaded it today) so any pointers would help.
Thanks so much in advance.

  • 0
    TI__Expert 5710 points

    Hi Ben,

    I believe this model only works with transient sims, please see WEBENCH to find DC values.

    Thanks,

    Dino Maslic 

  • 0 in reply to Dino Maslic
    Prodigy 20 points

    Hi Dino,

    Thanks for your reply! My end goal is to perform transient simulations, and the DC value was just a sanity check.
    My ultimate goal is to connect this DC/DC converter to a capacitor as I need to charge the capacitor and make sure that the DC/DC converter can survive the initial current spike when the voltage across the capacitor is 0.

    Regards
    Ben

  • 0 in reply to Ben Tay
    Prodigy 20 points

    Some updates:

    I was able to get the DC/DC converter to output 15V as expected, I needed to select the option "0 initial vlaues", but some unexpected behavior happened when i connected it to a capacitor to simulate the capacitor charging.

    Theoretically, I know the capacitor should charge up within 4ms, as using an ideal voltage source yields the following results:

    However, putting this at the output of the DC DC converter yields some weird results:

    It takes about 1ms to settle to about 15V, and at t=2ms i close the switch to enable the capacitor charging, which doesn't complete in 4ms as expected.
    What could be causing this?

    Regards
    Ben

  • 0 in reply to Ben Tay
    TI__Expert 5710 points

    Hi Ben,

    Could you provide waveforms of the SW node and inductor current so I can get a better idea of what the device is doing?

    Thanks,

    Dino

  • 0 in reply to Dino Maslic
    TI__Expert 5710 points

    Closing out due to inactivity.