Impedance matching buffered voltage divider

Discussion in 'General Electronics Chat' started by vortmax, Mar 19, 2013.

  1. vortmax

    Thread Starter Member

    Oct 10, 2012
    103
    18
    I have a quick question about a buffered voltage divider. I have two signals that can range from 0 to 5V that I need to scale down to 0 to 3V. I've chosen to do this with a voltage divider buffered through an opamp (schematic attached).

    According to the data sheet, the output impedance of the voltage source is 470 ohms, and it wants at least 1 Mega Ohm of impedance on all analog and digital lines.

    It seems to me that as long as the total equivalent resistance of the divider (R11 + R12) is ~1 mega ohm that the all will be well. Is this true or am I over simplifying it?
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,016
    3,235
    That sounds correct.

    You may be aware of this, but if the op amp only has a 3V supply, then the op amp must be a rail-to-rail type.
     
  3. vortmax

    Thread Starter Member

    Oct 10, 2012
    103
    18
    Awesome. Thanks. Yea the amp I'm using is rail to rail.
     
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