Unicorn Meta Zoo 9: I believe that I have conformed to the guidelines in the datasheet. This chip predates big cheap ceramic caps, I think. They need to be rated above my voltages also. CuF is an SMD tant: Or offer an alternative regulator that is more linear at high frequency As suggested in this answer? Schematic of the regulation circuit.

lm2940 datasheet

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Or offer an alternative dstasheet that is more linear at high frequency As suggested in this answer? This chip predates big cheap ceramic caps, I think.

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Now my confusion starts with ESR datassheet capacitor type The capacitor you linked to is 22pf, which is only one millionth of the specified value. Alas the data on minimum ESR is l,2940 sketchy nothing for “C” case for exampleso you have to guesstimate from just these two graphs or get an ESR meter and measure it, or even just with your scope and a function gen that can hit those MHz frequencies where you see oscillation.


lm2940 datasheet

Please see updated question with attached schematic. By using our site, you acknowledge that you have read and lm240 our Cookie PolicyPrivacy Policyand our Terms of Service. Sign up using Email and Password.

LM Datasheet PDF –

Could that contribute to the oscillation? NB – in the pdf you cite they say: Sorry, that was my mistake. The best answers are voted up and rise to the top. Sign up to join this community.

As, if anything, your ESR may be too high it seems I’d try another cap in parallel. Improving the question-asking experience. Sign up using Facebook. As a general rule, the higher the voltage rating the larger the size so a 0. Email Required, but never shown. If you look at page 18 in its datasheet the ESR dstasheet the uF, 6.

LM 2940 T-5.0

Home Questions Tags Users Unanswered. Read 1 time previous topic – next topic. I was using the above to supply 5v to my Atmegap-pu project in my automotive environment for controlling the signal that turns on some lights via Mosfet. I’m encountering some instabilities in my regulated voltage supply. Does anyone have any ideas how I might stabilize this output? I live in Lincoln. It can be 2x to 4x higher at 2 x mains frequency.


Is the scope trace shown when under load?

lm2940 datasheet

How do we handle problem users? Sign up or log in Sign up using Google. However, I have found that higher-frequency fluctuations in voltage are not properly regulated by the LM, causing intermittent brown-out of the MCU.

Also why do you have 18MHz 1.

lm2940 datasheet

For reference, this is the LM datasheet. Whether the or Hz ESR is relevant is tbd BUT as you have a 2 x mains input ripple that the regulator is dealing with this may llm2940 the instability trigger.

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