• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 40 subscribers
  • Views 413 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

TINA/Spice/TPS54350: Input voltage troubles with simulation; sim fails with Vin above 10.6V

CPage
Prodigy 20 points
Part Number: TPS54350
Other Parts Discussed in Thread: TINA-TI,

Tool/software: TINA-TI or Spice Models

I have the TPS54350 spice model and am working in Orcad pspice.

I have built the circuit modeled in figure 24 of the datasheet (page15) which should give me 3V3 out with Vin from 6V-18V, with a small differences being the Rt pin is grounded, not floating and I do not have the snubber in circuit on the low side FET. When I simulate the design with Vin @ 12V, I do not get the 3V3 output, the output doesn't rise above 25mV. 

I found if I change the Vin from 5V to 10.6V, I get the 3V3 output as expected, but if I exceed 10.6V the output does not meet expectations (picture below w/Vin@10.7V), and appears to be cycling around 600mV so I am wondering if there is something going on internal to the model. Has anyone experienced any issues with this model at this voltage level?

  • 0
    TI__Expert 3140 points

    Hello,

    I simulated the setup you configured. Below is the test bench and simulation result.

    Test bench:


    Simulation result:



    Looks like the results are proper. PFA the project TPS54350_PSPICE_TRANS.zip.

    Thanks & Regards,

    Arpan Gupta

  • 0 in reply to Arpan Gupta
    Prodigy 20 points

    Arpan, thanks for looking into this. I think my problem may be related to the MOSFET. I made a model from the device curves for the FDR6674A used in the datasheet, and I have a manufacturer model of another MOSFET and when I put either of them into your testbench, I get the same failed output.

    One thing I did realize the MOSFET recommended to me by a colleague has a Qg of 104nC which far exceeds the maximum Qg recommended in the datasheet (50nC) for the low side driver, so that might also be part of my problem here, so I think I have some more work to do on this.

    Again, thanks for checking and verifying the TPS54350 model for me, I will continue to see if I can get stuff sorted out on my end.