WEBENCH® Tools/TPS543B20: Design can not be created

Hi AnBer,

Thank you for reporting this issue. We are looking into the root cause. We will get back to you on this.

Thanks & Regards,

Praveen

Hi AnBer,

Currently the WEBENCH designs have been restricted for TPS543B20 for high duty cycle cases due to limitation in WEBENCH model for this device.

However this might not necessarily be limitation of product. Hence we have requested a product expert to further assist you.

Thanks & Regards,

Harish

Hi Harish,

Thanks for the input.

Is there a way to display some comments to explain this instead of Webench just returning an error message?
Just returning an error message does not give a good confidence level to use the tool further...

A.

Hi AnBer,

Will you able to use to Pspice mode to run the simulation for your design? You can also use the EVM to evaluate the design too.

Kit

Hi Anthony,

    We have given the feedback to the WEBENCH team to update the error message to let the user know on what the limitation is.

Currently, you can try increasing the VInmin to 5V instead of 4.5V. Then creating a design using WEBENCH. Then you can use simulation to check if the design works down to 4.5V to get confidence on the design.

Please let us know if you have more questions.

regards,

Gerold

Hi Anthony,

    Just checking if you were able to create a design using the above conditions.

Regards,

Gerold

Hi Gerold,

Is the limitation in the Spice model itself or in how Webench make use of it?

I am trying to find out if it is possible to simulate in TINA-TI/pspice instead.

We have seen an issue with TPS54A20 where the exported model for TINA-TI was not fonctionnal.
See https://e2e.ti.com/support/power-management/f/196/t/877265
We got an offline feedback about it:
The exported TINA transient model simulation is running without any errors. But Output voltage is not settling to expected value and hence we had disabled the startup simulation on WEBENCH. However TINA export of startup was enabled which should be disabled. We have disabled the TINA export on WEBENCH for now.

Is it an issue of the spice model speciifcally or of the webench simulation/export fonction?
Do you plan to have some pop up message or log that explain what is being enabled/disabled when exporting from Webench?

Thanks,

A

Hi Gerold,

Thank you for your answer.

I've tried to simulate design with a Vmin=5V instead of 4.5V.

At first sight it seems to work however i'm embarassed with the fact I cannot change the "User Preferred Frequency" parameter. I would like a 1.5MHz switching frequency but the valid range seems to be limited from 0.3 to 1.133 MHz.

Hereunder the design file:

https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=8564087F11563F1D

I do not see why there is such limitation ?

For standalone device, switching frequency range should be from 300kHz to 2MHz.

Due to this problem, I cannot estimate the Lpd(W) and ICpd(W) parameters for my application.

Thank you for your support.

Mickaël.

Hi Mickael,

     Its probably the minimum toff of the device (250ns) that is limiting this application to be operated at high frequencies for this duty cycle. If you do lower duty cycles, you will probably be able to run it at higher frequencies.

Regards,

Gerold

Hi Gerold,

So, does it mean I have to choose a lower switching frequency such as 1.1MHz for my design to work properly?

What can happen if I keep a switching frequency of 1.5MHz with:

- 4.5<Vin<5.5

- Vout=3.3

- I=10A

Mickaël.