so im trying to clean my 5v supply for the dac with inductors, and confused about which value to use. i'd like to make the filter aggressive and actually target down to 15khz to where the inductors have an effect.
current draw is about 15-20ma? regulator- salas shunt/lm317
i think i remember reading somewhere 300uh+3ohm parallel is a good place to start but the chart i looked at somehwhere had 1mh for 15khz which's my target
please help. thank you
current draw is about 15-20ma? regulator- salas shunt/lm317
i think i remember reading somewhere 300uh+3ohm parallel is a good place to start but the chart i looked at somehwhere had 1mh for 15khz which's my target
please help. thank you
Start off with a 4.7uH inductor from TDK which has about 30mohm ESR. If you don't want to use any series resistance to achieve your damping, you'll find in simulation you need a 2700uF capacitor to avoid significant peaking (say under 0.5dB). However this value gives you a -3dB of 1.7kHz, much more filtering than you were aiming for.
If you don't want such a big C, say 330uF instead then you need to add 0.1ohm in series with your inductor. This can be done fairly cheaply with a couple of high current ferrite beads (TDK MPZ2012S102 type). Then your corner frequency is about 5kHz.
If you don't want such a big C, say 330uF instead then you need to add 0.1ohm in series with your inductor. This can be done fairly cheaply with a couple of high current ferrite beads (TDK MPZ2012S102 type). Then your corner frequency is about 5kHz.
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