Selecting right buffer for dac

Discussion in 'General Electronics Chat' started by Vindhyachal Takniki, Mar 16, 2015.

  1. Vindhyachal Takniki

    Thread Starter Member

    Nov 3, 2014
    348
    6
    I am using TI's Dac8568 (16 bit 0-5V).
    I need a buffer IC at output of each dac.

    1. Buffer IC should be operate from single supply 5V.
    2. Able to supply upto 10mA (flexible on this spec)
    3. Rail to rail; full 0-5V
    4. Low offset
    5. Temp: -40C to +85C


    I looked at EL5127 & MAX4208.
    1. EL5127 is low power & rail to rail. When load is +5mA the drop is 80mV.
    2. MAX4208is very low pwer, low offset, rail to rail. Only thing I didn't find the drop in output voltage with load?


    Any other buffer which I can select for better performance with 16but dac.
     
  2. Gibson486

    Member

    Jul 20, 2012
    199
    12
    A buffer will usually only make things worse. You also have to worry about the offset voltage as you have found. If you are really concerned, then get a "precision op amp". They cost more, but if you need it, you need it. That said, you should be more concerned about about noise. There is only a 76uV difference in between q values.

    Your specs are not hard to find at all, really, but they will cost more than your typical 90 cent op amp.
     
  3. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,531
    1,248
    Also, "rail-to-rail" is a *very* relative thing. While many opamps have an input common mode range that includes and exceeds the negative supply rail (god bless the LM324), none have an output that will swing down to 0.00 V, or anywhere near within 76 microvolts (1 LSB) of the positive rail at any current, let alone 10 mA. What is it you are trying to do? Can you post a schematic, block diagram...anything?

    ak
     
  4. Vindhyachal Takniki

    Thread Starter Member

    Nov 3, 2014
    348
    6
    Thanks for response. I have selected ISL28134, it has low offset, high settling time & around 100mv drops from rails at 10mA load.

    One query:
    Should I connect a 10ohms & 0.1uf cap at the output of buffer before finally giving at output terminals.
     
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