opamp & its current

Discussion in 'General Electronics Chat' started by aamirali, Mar 1, 2012.

  1. aamirali

    Thread Starter Member

    Feb 2, 2012
    1. I have connected an push-pull opamp only VDD & VSS to 15V power source which is some inches away from IC.

    2. Without decoupling cap current was 40mA & with decoupling cap curent reduces to 5mA. What's reason behind this.

    3. This 5mA current consmption increases if I touch the opamp with my finger only casing not the pins & again come back normal after that?
  2. crutschow


    Mar 14, 2008
    It draws more current when it is oscillating. And the oscillations are sensitive to stray capacitance, such as from your finger.

    So you've just encountered one of the reasons decoupling caps should always be connected directly from all IC power pins to ground. But many beginners seem to think that it's optional. :rolleyes: