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Question regarding ADA4899-1

I have a customer with the following question:

  • (1)  I am using the SOIC package, which has two –Vs pins.  Is it best connect both 4 and 5, or just pin 5 (see figure and data sheet excerpt below)?
  • (2) Input bias currents can be reduced from -6uA to -0.1uA by tying the ~DISABLE pin to the +5V rail (at the expense of increased wide band noise). My question is does this have any positive or negative affect on the Input Offset current Ios vs temperature specification?, which is specified at 3nA/C (typical)?

   “ ... The SOIC is slightly different with the intent of both isolating the inputs

from the supply pins and giving the user the option of using the

ADA4899-1 in a standard SOIC board layout with little or no

  1. modification. Taking the unused Pin 5 and making it a second

negative supply pin allows for both an input isolated layout and

a traditional layout to be supported.”

Parents
  • Thanks Jino.   Just following up on the question

    Connecting pin 8 (DISABLE) to +5V activates the input bias current cancellation circuit of ADA4899-1, thus lowers the input bias current. In this state output-referred offset is minimal but doubles the input-referred current noise. I will have to investigate further for the effect of this configuration on the Input Bias Offset Current Drift of the device.

    Rich

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  • Thanks Jino.   Just following up on the question

    Connecting pin 8 (DISABLE) to +5V activates the input bias current cancellation circuit of ADA4899-1, thus lowers the input bias current. In this state output-referred offset is minimal but doubles the input-referred current noise. I will have to investigate further for the effect of this configuration on the Input Bias Offset Current Drift of the device.

    Rich

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