Electronics > Projects, Designs, and Technical Stuff
14.4V ground reference for ADC
Simon:
--- Quote from: Arjunan M R on May 30, 2019, 04:50:35 pm ---I am using a 100nF ceramic and 10uF tantalum for bypassing ADC , DAC and VRef.
Is that enough?
--- End quote ---
Do you mean you have one 100nF ceramic and one 10uF tantalum for all 3 or that they have a pair each?
Siwastaja:
--- Quote from: Arjunan M R on May 30, 2019, 04:13:55 pm ---Then why do manufacturers says to use lower value ceramic and also higher value tantalum together for bypassing??
--- End quote ---
Higher value tantalum has more inductance due to larger package, which, together with high ESR, prevents it from reacting to high-frequency noise.
In parallel, they filter different frequency ranges.
I comment about the inductance and package, because to be really effective, the small 100n cap has to be in the right place.
When paralleling low-ESR capacitors of different size, there is a risk they form oscillating resonance frequency ranges, together with stray inductances. But when the larger capacitor has some ESR, it dampens this effect, like a shock absorber does with mechanical springs. Hence it's very common to see a combination of a small, low-ESR capacitance, combined with a much larger capacitance, but with considerable ESR. Tantalum is a very effective type for providing well controlled ESR. Of course, a MLCC + separate series resistor can be used as well.
Arjunan M R:
--- Quote from: Simon on May 30, 2019, 04:59:45 pm ---
--- Quote from: Arjunan M R on May 30, 2019, 04:50:35 pm ---I am using a 100nF ceramic and 10uF tantalum for bypassing ADC , DAC and VRef.
Is that enough?
--- End quote ---
Do you mean you have one 100nF ceramic and one 10uF tantalum for all 3 or that they have a pair each?
--- End quote ---
A pair of 100n and 10uF for 3 of those.
Arjunan M R:
which capacitor i need to use in here?
electrolytic, tantalum or MLCC ?
Arjunan M R:
--- Quote from: Arjunan M R on May 31, 2019, 04:46:45 am ---which capacitor i need to use in here?
electrolytic, tantalum or MLCC ?
--- End quote ---
i will use tantalum.
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