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LM2941 Output capacitor value and ESR

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geotFM

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Hello.I am building a small power supply with LM2941 to test small fm transmitters etc.I have added two VK200 chokes in series with the output.I attach my configuration below.Will there be any problems with my configuration in terms of stability,ESR?Will the 220uF/25V electrolytic withstand outputt ripple current?
 

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Hi,

Will the 220uF/25V electrolytic withstand outputt ripple current?
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Nobody can tell you. Read the datasheet.

Note: Please be sure the given ESR is specified at about your swtiching frequency. The 100Hz_ESR may differ form the 100kHz_ESR. --> Datasheet.

From your given values it should be stable.

My recommendations.
* the bottom inductor seems to be useless, because there is "Ground" on both sides.
* I´d put a 22uF or a little higher value at the left side of the inductor, and the bigger 220uF one at the right side of the filter. This give more stable output voltage with a switched load.
* I dont like the pure LC filters because fo their (huge?) resonance. In your case the resonance frequency is at 160kHz. At least add a damping RC.

Klaus
 

To maintain a stable output the LM2941 regulator gives very specific ESR values for the 22uF+ output capacitor.,..thats what the theory and datasheet suggest.
 

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