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Taking the Kinetis L FRDM board to the next level, a real product

Question asked by Steven Cohen on Apr 18, 2013
Latest reply on May 8, 2013 by Zhe Tian

Ok, customer got their first product working using the KL25 FRDM board with an attached daughter card.  They are using USB in their product.

 

1.  The FRDM board doesn't add much in they way of projection on the usb lines , just a few Schottky diodes.  We have noticed some noise coupling into the laptop that connects to the FRDM board when power is applied to the board other then USB power.  Any suggestions on what we should add for additional USB protection?

 

2.  What should the power scheme be if 3.3v would be applied equivalent to P3V3 KL25 from a different power source, but if USB is attached, will it be able to enumerate?  Sort of new to designing a USB product.  We have already cut the path for the P5V KL25Z trying to address noise for test.  If we plan on adding the debug header, are we missing anything other then decoupling caps on power?

 

 

 

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