DC-DC of TPS65950 getting broken, beagleboard

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1

Hello,

I manufactured and produced a board that basically is the same as the beagleboard.

  1. I got it working for some hours (configuring linux), and after that it suddenly stopped responding. The TPS65950 was really hot (really,really hot!), the VDD1 module was consuming too much current and the output was 2.6V instead of the 1.3V it should be. My conclusion is that the module got broken.

  2. I cut some tracks and I supplied it with an external source. I worked again. I continued configuring linux on it. After some hours, it suddenly stopped responding again. I realized that the VIO module of the TPS65950 was consuming too much current and it´s output was 0.4V instead of the 1.8V it should be. My conclusion is that the module got broken.

With this evidences I compared the routing of my board with the routing of the beagleboard and I realized that in the beagleboard the connections between the outputs of the DC-DC (VIO module and VDD1 module are DC-DC) and the coils are made with planes instead of tracks. In my board the connection between the output of the modules and the coils are made with thin and long tracks.

are my DC-DCs getting broken because of the bad routing?
do you remember any similar problem while you where manufacturing prototypes and designing the beagleboard (or other similar boards)?
if you did not have any problem similar to mine, why you used planes in all the connections of the coils?

Thank you very much, I really appreciate your help.

Andrés Cecilia Luque

2

I have no idea what your issue may be. We have never had any issues of any consequence on the TPS65950 over the last three years. If you chose not to follow the layout, there may be other issues that you have, not just the skinny etch…You may have component issues. And the PMIC may actually be fine and the issue is in other parts of the board where too much current is being consumed…

As to why we did what we did, all I can say is many years of experiences. You always want to make power planes as big as you can. There is no valid reason not to.The greater the etch the lower the resistance and the lower the voltage drop.