current budget

Discussion in 'The Projects Forum' started by cgama, Mar 19, 2012.

  1. cgama

    Thread Starter New Member

    Dec 23, 2011
    19
    0
    Hi everyone

    I need to calculate the battery life of my circuit.
    Someone told me about the "current budget" method where you get the current drawn from each chip and resistor and sum.
    Well, the question is when reading the chip's datasheet, should I include the input bias current or the quiescent current?

    Thanks for all your help!!!
     
  2. #12

    Expert

    Nov 30, 2010
    16,278
    6,791
    Not the bias current. yes the quiescent current. and the current used to do do the switching and power the loads.

    Much more accurate to build it and measure it because datasheet specs contain "worst case" idle current. Still, you can calculate the answer and then be happy that the chips don't actually use the worst case specification.

    Keep in mind that all currents happen across time. You must multiply those together to get milliamp-hours or amp-hours, and that is the form of specification the battery will have.
     
  3. cgama

    Thread Starter New Member

    Dec 23, 2011
    19
    0
    Thank you very much for your help!!! :)
     
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