Workbench change design for TPS54560

Rene,

I created the design with your input specifications for the TPS54560 and I do not see any temperature issues particularly to cause shutdown of the IC. However, I have contacted the product line for this for further feedback.

Would you be able to provide the ambient temperature value and if you made any further changes to the default design (like Switching frequency, components used, etc.)? If you would like, you could use the 'print' button at the top right corner inside WEBENCH® Designer and attach the  pdf report with your reply.

Would it be possible for you to share the details of the exact schematic of the built board along with the individual components used (BOM)? This might also help in further debugging the problem.

Regards,

Amod

Hello Amod

I made a printscreen of my layout and add the print of the design I made.

the Layout

the thermal simulation

the thermal simulation 2

Hi Rene,

Is T900A some type of inductive filter? If so it could have some resonance as the load increases causing oscillation and over voltage at the VIN pin of the TPS54560. I suggest checking the VIN pin voltage to see if this is the case. If you see oscillation here please try removing the filter or shorting it to see if the issue is gone.

Can you also share the full schematic of your board? I didn't see it in all of the attachments.

Best Regards,
Anthony

my schematic

Hi Anthony

there is no oscilation at the input of the TPS.

Nevertheless I removed the filter (yes, your are right) but nothing changed. the diode an the TPS getting hot over 100mA.

I made two screenshots from osciloscop.

This one are the input voltage at the input pin of the TPS

and this is the output voltage and the the switchoutput of the TPS.

Kind regards

René

Hello 

Today I changed the diode "CD214B-R3600" to a "VS-50WQ10FN-M3" and now it works. So the recommended "CD214B-R3600" is definitely the wrong one.

I didn´t find anything about the reverse recovery time at the datasheets - could it be that or whats the reason for that?

Thanks

René

Rene,

Good catch on the diode! I did not look closely at the diode selection and I definitely recommend against using the CD214B-R3600. Faster reverse recovery time and low reverse recovery charge is important for best performance with the TPS54560 and switching power supply applications in general. As you noted this is often not shown in the datasheet of the diodes so it's not something we can filter directly the component selection. However generally a lower voltage schottky diode will have better performance.

Amod and I are going to improve the diode selection for the TPS54560 in WEBENCH to suggest diodes with better performance.

Best Regards,
Anthony