Tweeting issue on TPS40305DRCR design

That effect happens occasionally.  here is some information on it:

http://www.kemet.com/Lists/TechnicalArticles/Attachments/62/2007%20CARTS%20-%20Reduced%20Microphonics%20and%20Sound%20Emissions.pdf

Thank you John for your reply,

Can you take a look on the relevant schematic / layout part in order to see if there is any visible solution without changing the layout.

Anyway, we would like to avoid using tantalum capacitors…

If so, it will be very helpful if you will attached any email address for this session.

Thanks again!

Erez.

I don't directly support TPS40305.  I often answer general questions on the forum though.  Let's see if the appropriate person can look at it.  Are you going to post your schematic and layout?  Do you have varying load conditions that may be causing this?

Yes, there is a varying load, but its frequency is 60Hz (which is not the twitting sound we are hearing).

Any way this DC2DC output is mainly connected to other secondary DC2DCs, so I am not sure the twitting issue has been caused by the load.

Till now TI support was very fruitful by asktexas@ti.com usage, but currently they have directed me to one of their support centers which isn't cooperative, so I started this post session…

Can you direct me to some supportive email?

Thanks!

Erez.

I have forwarded you request.

Erez,

We'll need to you provide the schematic and layout so that we can review it.

Have you checked the low-frequency loop response, especially at light load and near the resonance frequency with either the Excel TPS40K Loop tool linked from the product folder or with a design in Webbench?

I'm perticularly interested in the phase dip at the L-C resoance, which will typically be in the audio band.

Thank you John!

Hi Peter,

I haven't used the tool you just mentioned, Can you please provide me a link?

Beside I need an email address for the schematic and layout shipment…

Thanks!

Erez.

Erez,

Here is the link to the excel design tool: http://www.ti.com/lit/zip/sluc263 

I'll send you a message with an e-mail address.