Re: Use 3.3 volts oscillator with AD9851


This question (interfacing between voltage domains) is one I frequently had to deal with.

I have seen ICs (not this one) powered by 5V where all the inputs were compatible with 3.3V or even 2.5V signals ... EXCEPT for the clock input which required a full 5V rail-to-rail swing.  That's not very common, but it can happen.  Always consult the datasheet.

In this case the AD9851 datasheet apparently shows the input must swing between 1.5V and 3.5V at minimum.  So yes, I think you could bias a sine or square wave around 2.5V, and as long as its swing exceeds 2Vp-p, it should work.  Be careful if the source pulsewidth isn't symmetrical.

Become intimately familiar with the datasheet, and if in doubt, consulting an ADI field engineer might be a good idea.

Active converters (amplifiers) are OK but not always needed and IMHO you are better off without them if you don't need them.


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