TPS543B22: webench tool cannot produce desired output

victor sabino

Prodigy 160 points

Part Number: TPS543B22
Other Parts Discussed in Thread: TPS543620, TPSM843B22EVM

Tool/software:

Hello, I came across this device and the TPS543B22EVM evaluation PCB.

The specs say the output can be configured for up to 7V, 20A.

I use the webench tool and it does not allow me to obtain 7V.

what am I doing wrong?

Regards,

Victor

3 months ago

0 David_Daniels 3 months ago

TI__Mastermind 23965 points

Victor

What were the inputs on intake panel?

I am guessing here.

Make sure the input voltage is greater than output voltage?

and 7V output designs tend to have higher power dissipation, so lower the output current.

0 victor sabino 3 months ago in reply to David_Daniels

Prodigy 160 points

Hi David,

this works:

this does not:

0 David_Daniels 3 months ago in reply to victor sabino

TI__Mastermind 23965 points

Okay, at 7v and 20A, the power dissipation is high and Tj exceeds 125C at 30C ambient.

Lowering the output current for 30C ambient temperature or lowering ambient temperature should for 20A yield a result.

0 victor sabino 3 months ago in reply to David_Daniels

Prodigy 160 points

thanks for the reply.

I tried lowering the temperature and it still did not work:

0 David_Daniels 3 months ago in reply to victor sabino

TI__Mastermind 23965 points

Ambient -35 works The power dissipation is high from the higher input voltage.

use https://webench.ti.com/power-designer and enter your specs and more suitable device should be presented

0 victor sabino 2 months ago in reply to David_Daniels

Prodigy 160 points

Hi David,

now I'm trying 5V / 2A output, and it still does not work.

Something does not seem right.

regards,

Victor

0 David_Daniels 2 months ago in reply to victor sabino

TI__Mastermind 23965 points

Here is a link to 7V output design, if you have not been able to get a result.

https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=AA5CDC8E68790429.

Interesting that the 5V / 2A will give an error message for phase margin too low, but a 7V can give a result when lowering the ambient temperature. I will forward to webench team to look into the issue. Seems the algorithm is not robust for corner case designs.

the 7V design is using 16V output capacitors. The TPS543620 is a 6A device based on the same controller and yields a 5v output design and using 10V capacitors.

0 Sateesh Goudappanavar 2 months ago in reply to David_Daniels

TI__Intellectual 2350 points

Hi victor sabino,

We are able to replicate the issue, this is a bug.

We have started working on this issue. We will keep you posted as soon as we have any progress.

Thank you.

David_Daniels thank you for routing this issue to WEBENCH team.

Best Regards,
Sateesh A G

0 victor sabino 2 months ago

Prodigy 160 points

Thanks to all your responses!

Glad that I was able to identify a bug to improve your useful tool!

yesterday, after not getting good results with webench, we opted to allow webench to suggest alternative solutions.

We decided to purchase the TPSM843B22EVM to test in our lab. Webex allowed the following specs:

Customize TPSM843B22RDGR ‑ 9V-15V to 5.00V @ 20A

Input:

DC 9 V - 15 V

Output:

5 V at 20 A

Temp:

30 °C

Regards,

Victor

0 Sateesh Goudappanavar 2 months ago in reply to victor sabino

TI__Intellectual 2350 points

Hi victor sabino,

Thank you for your positive approach, and please accept our sincere apologies for the inconvenience you encountered.

We have identified and resolved the issue, and successfully completed testing within our internal servers. The updates are scheduled to be deployed to production today. Should there be any unforeseen delays, the updates will be reflected in production no later than 3rd July 2025, EOD.

We greatly appreciate your patience and continued support.

Thank you once again.

Best Regards,
Sateesh A G

0 Shaheen Makandar 2 months ago in reply to Sateesh Goudappanavar

TI__Expert 3110 points

This fix is now available on ti.com

Thanks for your patience.

Best Regards

Shaheen

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TPS543B22: webench tool cannot produce desired output