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REF5040: LOW noise voltage reference

Part Number: REF5040
Other Parts Discussed in Thread: OPA625, ADS9110, REF6141

Hi  ,

I just read   TIDUB85  ( Reference design  for 18 bit 2MSPS   DAQ )   .  particularly  the part     that is related to voltage reference design  is my  issue .


 Now  spouse that I want to use   that reference  for  deriving  4  SAR  ADC  ,    Can  OPA625  derive  4  ADC ,      The  ADC  Vref   average current is   100 uA   but   cause  it is  average current  I  don't want to have

concern in worst case   situation . I want  to  reduce the  noise as much as possible  and try to use  the  suggested low pass filter on TIDUB85


And  don't i need  to use another  10uF capacitor   close to ADC ref pin   as  storage capacitor ?

thank you very much

  • Hi Vahid,

    The ADS9110 uses an average of 1.25mA of current at max data rate and range, however, the inrush current spikes can be as large as 50mA.

    In order to have the best performance, each ADC should be buffered independently. This is due to the fact that the noise created from the fast-changing current can couple into the other ADCs. Also, each ADC does need its own capacitors as close as possible.

    We also offer the REF6x41, which is a voltage reference with an integrated buffer, and a pin for filtering. As mentioned before, however, you would need 4 of these since one can't drive all 4 ADCs from a single buffer.

    Regards, Diego
  • thank  you   for  your reply, as  I mentioned in my  first  post I was  focusing on only  voltage  reference part  of  that evaluation broad    , I  am not going to use  ADS9110  ,   I am using   AD7693, but  want to use voltage reference  from TI  , and get the benefits  of filtering  method   which  TI   mentioned on its  evaluation broad reference .


    For decreasing  the cost I  try to use  only one  vref  IC with   appropriate buffer  that can drive  4 ADC (ad7693)

    and   why when  we  buffer an REF6141  out put  with appropriate  buffer  ,yet it can not  drive  4  ADC, 

    I think when we  use  proper  buffer then   REF6141    only  should be able to drive  buffer  input current - since  buffer  input current is low  we dont have much of concern- not  total ADC vref  input current

    thanks   a lot