Hmmm, yes, I see that. Not at ALL congruent with the Jan Didden graphs (https://cdn.shopify.com/s/files/1/1006/5046/files/V4_JW_F7.pdf), which show the LM317 noise to be ≤ 0.2 microvolts across the spectrum 10 to 100 K Hz. ????
Ok, I see......what THEN would the LM317 noise be? For the band width shown (100KHz), would it be 0.2uV/√Hz, or 63.2 microvolts? That would be -84 db, which is quite close to the figure quoted here (with a 220uF adjustment leg cap and a 220uF output cap):Simple Voltage Regulators Part 1: Noise - [English].
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Well, I believe that tutorial (Spectral Noise Density to RMS Noise | Analog Devices)
Pretty much goes along with my calculation---the Didden graph shows ≤0.2uV noise density, times √100 KHz; gives ~63 uVolts; or 84 db below 1 volt. Eh?
Pretty much goes along with my calculation---the Didden graph shows ≤0.2uV noise density, times √100 KHz; gives ~63 uVolts; or 84 db below 1 volt. Eh?
is the 317 noise relative to the 1.25 volts at the reference pin?
If one is using the 317 to give a regulated output of 5Vdc, then the voltage divider feeding back into the ref would be quadupling the ref voltage. Does that double or quadruple the noise on the output line?
What if one were outputting a regulated 25Vdc?
Does the noise get multiplied up for that?
If one is using the 317 to give a regulated output of 5Vdc, then the voltage divider feeding back into the ref would be quadupling the ref voltage. Does that double or quadruple the noise on the output line?
What if one were outputting a regulated 25Vdc?
Does the noise get multiplied up for that?
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