AD5272 / AD5274 Power-up sequence

Hello,

Currently reading the datasheet of these components, I wish to ask you some more information about the power-up sequence.

On page number 24 of the datasheet (revision C), I can read that the ideal power-up sequence is : 1.VSS, 2. VDD and then Va/Vw

But on the AD5272 FAQ (http://www.analog.com/en/digital-to-analog-converters/digital-potentiometers/ad5272/products/technical-documentation/index.html), under the question "Is there a power-up sequence?" I read that the power-up sequence is 1. VDD, 2. VSS and then Va/Vw

So I wonder which sequence is the right one?  Is it really important ?

I thank you

S.M.

  • 0
    •  Analog Employees 
    on May 8, 2012 11:04 AM

    Hi Padbol,

    The power sequence is important bc this avoid to stress the part.

    It is always recommended to power the substrate of the circuit first.

    As a simple example, when you connect your board to any supply, are you connecting first GND? or VDD?

    In this case, the substrate is a n-well, so the first supply must be the most negative, in this case Vss.

    If the substrate is p-well, the substrate is connected to Vdd.

    Answering your question, the DS should have priority over any other document, so the correct supply sequence is Vss -> Vdd -> Va/Vw

    Let me know if something is not clear, please.

    Regards,

    Miguel

  • Thank you very much.

    That's exactly the answer I was expecting