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UCC21520: Convergence problem of a designed Gate driver

Fankai Wen
Prodigy 10 points
Part Number: UCC21520

Tool/software:

Dear whom it may concern,

Hi, I am designing a half-bridge gatedriver circuit with a bias circuit to drive the 800V mosfet. The basic idea is to generate a biased 20V voltage across the GS pin of the mosfet when the input is high and generate a biased -4V voltage across the GS  pin of the mosfet when the input is low. Now the circuit works fine without the Mosfet as attach TI simulation_HF_bias without mosfet. However, when I add the mosfet as TI simulation_HF_bias with mosfet, it keeps showing convergence problem. Can you please help me figure it out?

BTW, I failed to find any 800V MOSFET in your company website. Are you selling this kind of MOSFET?

Best regards,TI simulation_HF_bias without mosfet.tscTI simulation_HF_bias with mosfet.tsc

Wen Fankai

  • 0
    TI__Expert 6276 points

    Hi Wen,

    Thank you for your interest in our products and reaching out!

    The convergence issue can be resolved by doing the following:

    1. Select Analysis --> "Set Analysis Parameters"
    2. Select the hand
    3. Select "open"
    4. Select "Transient Convergence Solutions.PRM"

    This should adjust the analysis parameters to help with convergence issues.

    Fankai Wen said:
    BTW, I failed to find any 800V MOSFET in your company website. Are you selling this kind of MOSFET?

    Unfortunately we do not have MOSFETs rated for that voltage. Our highest voltage rated MOSFETs are 100V.

    Hope this helps with the simulation issues.

    Regards,

    Hiroki

  • 0 in reply to Hiroki Honda
    Prodigy 10 points

    Thanks for your reply and help! Now it works but can I ask the state of art of tuning these parameters? From what I can tell, I think it sacrificises the accuracy. Will this drive the simulation away from the real hardware? Thanks!

  • 0 in reply to Fankai Wen
    TI__Expert 6276 points

    Hi Wen,

    I am glad to help!

    That is a great point. This PRM increases the DC relative error from 1% to 10%.

    Decreasing this value in "Analysis Parameters" will increase the accuracy.

    Please feel free to play around with these parameters to your preference.

    Clicking on the "Help" button will bring up a window that describes what each parameter does and how it affects your simulation.

    Hope this helps.

    Regards,

    Hiroki