Rafael Dazcal

MC9S08LC60 VREFH and VREFL

Discussion created by Rafael Dazcal on Jan 6, 2011
Latest reply on Jan 6, 2011 by Rafael Dazcal

Greetings all,

 

I'm using a MC9S08LC60 MCU and I have VREFH and VREFL pins available externally in the micro-controller.

 

I want to connect this pins to different values than VDD and VSS, but I read the following instruction in the data-sheet:

 

"When available on a separate pin, VREFL must be connected to the same voltage potential as VSSAD."

 

Why is that? Why would it be available externally and not be connected internally in the MCU if the user has no control over it?

 

And why VREFH can't be lower than 1.8V?

 

Thank you

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