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Kinetis K22 in QFP144 high-current

Question asked by Jonathan Guy on Aug 14, 2014
Latest reply on Aug 14, 2014 by Jonathan Guy

I've done a number of projects with Kinetis MCUs, but I'm having real trouble with a K22 bring-up.  All boards show a high-current path from VDD to VSS as soon as VDD hits 0.5V.  I've triple-checked schematic pin-out (and PCB) against the datasheet pin out.  There are no parts on the board apart from decoupling capacitors and a couple of pull-up /down resistors.

 

The only pins tied to GND (apart from VSS, VSSA) are VREFL the dedicated ADC0_DMx pins.

 

My questions are:

 

1) Can anyone point me to a reference schematic for the K22 in a LQFP144?

 

2) I've no-connected COUT33, VREGIN, VBAT, USB0DP/DM.  Are there any special considerations on these or any other pins at power-up?

 

Any help appreciated.

 

-- JAG

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