K28 Vrefh pin connection option

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K28 Vrefh pin connection option

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jasonlarson
Contributor II

I have a design that is power sensitive put I also need accurate adc readings. For this reason I'm adding a external prec ref voltage source. I will not be doing measurements all the time and If I shut down the prec ref I can save about 100ua. The only issue is that the Vrefh pin into the micro will be floating. Will this be a issue? The data sheet says unused pins short go to VDD but what happens if I let it float? Since I will not be doing any reading I would think it should not be a issue. It will have a impedance to gnd through the prec ref chip. Would that be good or bad?

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jingpan
NXP TechSupport
NXP TechSupport

Hi Jason,

I think it is ok if it float to ground. Please see  this link:

https://community.nxp.com/message/419427?commentID=419427#comment-419427

Regards,

Jing