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Original question:

DAC8562: About logic input high voltage

DAC8562: About logic input high voltage, please confirm

Roland Meyer1
Prodigy 40 points
Part Number: DAC8562


Tool/software:

Hi,

we are using the DAC8562TDGSR in a new design.

Most of the boards are working well. On one we have problems with the analog output of the DAC.

It doesn't seam to understand the values that we send.  The supply voltage is 5V. The level of the digital control signals is 3.3V.

In this forum, I found an old thread talking about the required logic levels.

Your answer was: "If your VDD is above 4.5V, then 3.3V logic wont work. You need to use level translator for the same."

This seams to be in contradiction with the datasheet.

Could you please confirm which digital input voltage levels are required ?

Thank you in advance!

Kind regards,

Roland

  • 0
    TI__Mastermind 42273 points

    Hi Roland, 

    The VIH requirement is 0.7*AVDD. Meaning that 3.3V logic will not work at a 5V VDD (5*0.7V = 3.5V). I believe the original post you linked was trying to convey that 4.5V is going to be the minimum allowable supply for 3.3V logic in order to meet the VIH requirement. Really this number would be 4.7V VDD, but that allows for very little margin on VIH. 

    You would need a level translator for 5V VDD and 3.3V logic. 

    Best,

    Katlynne Jones