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input pin left open

Question asked by Ryan Short on Oct 18, 2016
Latest reply on Oct 19, 2016 by Serguei Podiatchev

I inadvertently left two input pins left open on the MPC8378:  TSEC1_COL and TSEC2_COL.  The TSEC1/2 interfaces are configured for RMII operation so these signals are not used, however per Freescale AN3665, they should have been pulled high.  The pins are not tied to traces at all so rework is not an option.  I am not experiencing any obvious functional issues, but I need to analyze what the potential effect of this design error is.  The only thing I can think of is extra power drain due to either the input oscillating, or significant cross over current flowing.  Can you please provide further insight regarding the effect of leaving an input open, and if the effect is increased power, how I might determine how much more power will be used?