WEBENCH® Tools/TPS54339E: Wrong voltage coming from webench circuit.

Prodigy 10 points

Replies: 1

Views: 38

Part Number: TPS54339E

Tool/software: WEBENCH® Design Tools

I am using the TPS54339EDDAR on a simple dc to dc circuit. My input is 18.5v and my output is supposed to be 7v. I used WEBENCH to come up with the circuit and ordered every component from the bill of materials. I replicated the schematic exactly with the components and have had the following result. The circuit begins to output a little under 7v starting at an input of 3.8v, then as the input voltage increases the output stabilizes around 7.5v and stays there until the input hits 17.5v. At this point the output drops to 2.4v. Webench designed the circuit to work at 18.5v so I don't understand what is happening. I made two of these circuit, one at 7v and one at 5v, both circuit are doing the same thing. the 5v one begins to output about 5v around 3.3v and then drops to 1.065v at 14v. I will link the webench items below as well as show an image of the circuit I have built. There is a possibility that I made an error putting it together but need someone else's eyes to see it. Any suggestions are appreciated.

7v - https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=86865E4BD1E10B28

5v - https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=B96034ABF0086C2B

1 Reply

  • Nicholas,

    Thanks for sharing your WEBENCH designs and observations. I checked the WEBENCH designs and they look fine - the electrical startup simulation also produces the correct output voltage. So, I suspect there is something specifically happening on the bench. Assuming you have exactly the same schematic and BOM as WEBENCH tool, in addition, can you share details about your board and its layout? I am requesting a product expert for TPS54339E to take a look at this issue.