• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 64 subscribers
  • Views 1145 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.

TINA/Spice/LMR36015: SPICE model parameters "mode=0" and "fastss=0"

siko19
Prodigy 30 points
Part Number: LMR36015
Other Parts Discussed in Thread: TINA-TI

Tool/software: TINA-TI or Spice Models

Hello everybody,

I want do do some simulations with the spice model of LMR36015FB (http://www.ti.com/lit/zip/snvmbq5) in LTspice.

In the LMR36015FB_TRANS.LIB on spice line 1 there are the two parameters MODE and FASTSS:

.SUBCKT LMR36015FB_TRANS AGND BST EN FB NC PG PGND_0 PGND_1 SW VCC VIN_0 VIN_1 PARAMS: MODE=0 FASTSS=0

Can you explain me the meaning of these parameters? Which values can be chosen? I didn't find any explanation in the model usage notes.

Thanks in advance!

Best regards,

Simon

  • 0
    TI__Guru 73682 points

    Hi Simon,

    I will ask our modeling team to review this.

    Regards,

    Tim

  • 0
    TI__Expert 3140 points

    Hi Simon,

    Below are the explanation of the parameters.

    MODE: The parameter MODE can be used to reach the steady state faster. Keep MODE = 0 to observe startup behaviour and MODE = 1 for faster Steady state.

    FASTSS: The parameter FASTSS can be used to reach the steady state faster. Keep FASTSS = 0 to observe normal startup behaviour and FASTSS = 1 for faster startup. Keeping FASTSS=1 reduces the startup time to 0.9ms. It also reduces the hiccup wait and restart time by a scale of 10.

    Thanks & Regards,

    Arpan Gupta

  • 0 in reply to Arpan Gupta
    Prodigy 30 points

    Hi Arpan,

    thanks for your fast answer!

    Ok, in both cases you say that it speeds up the time to reach the steady state. So what is the main difference between MODE and FASTSS? Could you please tell me a few more details?

    Which value combinations between MODE and FASTSS are useful?

    As I have seen in the subckt-file MODE sets the initial conditions of some nodes.

    Thanks in advance!

    Best regards,

    Simon

  • 0 in reply to siko19
    TI__Expert 3140 points

    Hi Simon,

    MODE parameter sets start-up/steady state simulation. If MODE=0, it will simulate for start-up else if MODE=1, it will simulate for direct steady state.

    FASTSS parameter sets the start-up time. If FASTSS=0, it will simulate for long start-up as described in datasheet. But if we set FASTSS=1, still it will be start-up simulation but start-up time will be reduced to 900us.

    This is the main difference between the two parameters. 

    I would suggest you to set MODE=0 & FASTSS=1, then you will be able to observe start-up behaviour of the device with less time. The simulation time will be less in that case.

    Thanks & Regards,

    Arpan Gupta

  • 0 in reply to Arpan Gupta
    Prodigy 30 points

    Thanks for your support!