ADC/Voltage Reference Oscillation

Discussion in 'General Electronics Chat' started by mercury3141, Jun 3, 2013.

  1. mercury3141

    Thread Starter New Member

    Jun 3, 2013
    I am using a LTC6655-2.5 along with a LTC2383-16. The capacitor I'm using is a 47 uF 6.3 V X5R. As suggested in the ADC datasheet I originally used the 1 ohm resistor. When I noted the oscillation I didn't have a good guess and shorted the resistor. I also tried smaller capacitors. The oscillation frequency is on the order of 1Vp and 700 KHz. It will be stable for some time then enter oscillation. I'm not certain if it's the voltage reference or ADC that is oscillating....or if it really makes sense to say since when connected they system oscillates.

    I've done some searches of oscillation problems with these components and haven't come up with much. As another guess I replaced all the components one at a time but the problem remains. As these are MSOP components it isn't easy to debug on the PCB I made.

  2. MrChips


    Oct 2, 2009
    Can you post a circuit diagram and perhaps a photo of your board?
  3. LDC3

    Active Member

    Apr 27, 2013
    I don't think that making the capacitor small would remove the oscillations since it decreases the time constant of RC (increases the frequency).
    Since you want to attenuate oscillations and the RC is probably connected as a low pass filter, it would be better to increase the capacitor or resistor to remove the oscillations.