ADP3339 minimum input power and tolerance

According to the datasheet ADP3339 has a 2.8 V to 6 V input voltage range. We currently use this device in our design which feed in only 2.48V at the input due to design limitation. I understand that this is not ideal but so far we have minimal fall-out. Without specifying in a new part, could someone please explain the impact of providing insufficient input power and the risk/failure symptoms?

Thanks.

Peter

  • 0
    •  Analog Employees 
    on May 26, 2015 8:40 AM

    Hi Peter,

    The part was not characterized at input voltages lower than 2.8V and there's no guarantee that the specifications in the datasheet can be met at these conditions without doing additional testing. May I know what your output voltage and load conditions are? Another issue that you might see with lower input voltages is that you might not have enough headroom to regulate the output voltage, hence, the PSRR performance of the part would degrade.

    Let me know if you really need to operate at 2.48V, I could run some more tests in the lab to check regulation/vout accuracy and Iq on several parts, although this might take a while to complete.

    Best regards,

    Jess

  • Jess,

    Here's our HW engineer's response to your question and his comments:

     

    in summary, we are using the ADP3339 to provide the 1.8V rails for the AD9788. Unfortunately for us we are using the 2.5V (or 2.48V) rail to provide for the LDOs.

     

    so according with the AD9788 datasheet:

    DVDD18

    Pmax = 1250 mW

    V = 1.8V;

    hence Imax = 700 mA;

     

    CVDD18

    Pmax = 110 mW

    V = 1.8V;

    hence  Imax = 62 mA;

     

    As I mentioned we are using a ADP3339  (max. 1500 mA) for each rail

    ******************

    It would be great if you can conduct further test to characterize the lower Power input (2.48V) and impact. We understand that this will require time but we are eager to hear some feedback from the manufacturer.

    Thank you for your support.

    Peter

  • Jess, I haven't received any follow up response to my request. Is it possible for ADI to test a few devices to help characterizing the device performance at 2.48V or lower?

    Thanks.

    Peter

  • Peter,

      The only thing we guarantee are the mins and maxes in the spec table.  Looking at a few parts

    on the bench at room temperature, from one date code and one wafer run, is very risky.

    Even if it looks good, and you have had good luck in the past, the next batch of boards that

    you build could have 50% failures with a different date code.  Additionally, we might do a fab

    transfer or a mask set revision to increase yield and meet all of the numbers in the spec table

    and maybe none of the parts would work in your system.  If this is a production design,

    and you chose the wrong part, the only suggestion I have would be to do a board spin and

    use the ADM7171 or ADM7154, both of which are less money than the ADP3339

    Harry


  • 0
    •  Analog Employees 
    on Jun 16, 2015 8:17 AM

    Hi Peter,

    Apologies for the delayed response, I'm still securing the board and ICs. Looking at this again though, I'd agree with Harry. It would be better to look at possible replacement parts that you could use in your circuit, pls see attached excel file, it contains information on several ADI ICs that you might want to use instead. For example, you can use the ADM7171 or ADP1752 for the DVDD_1.8V and ADP121 or ADP150 for the CVDD_1.8V.

    Best regards,

    Jess