ADC/Voltage Reference Oscillation

Thread Starter

mercury3141

Joined Jun 3, 2013
1
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.

Suggestions?
 

LDC3

Joined Apr 27, 2013
924
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.
 
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