January 15, 2019

LM2940 DATASHEET PDF

The LM/LMC positive voltage regulator features the ability to source 1A of output current with a dropout volt- age of typically V and a maximum of. The LM LMC positive voltage regulator features the ability to source 1A of output current with a dropout voltage of typically 0 5V and a maximum of 1V. The LM positive-voltage regulator features the Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

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What is the input voltage?

I just thought the OKIsr might be a little overkill in terms of cost for other similar stuff down the road. NB – in the pdf you cite they say: Hi Russel, thanks for the feedback. The average voltage at the input is around xatasheet.

I have used the LM in a number of designs with no problem using tantalum input and output caps. With such datashheet power involved you can go with the linear regulator, you shouldn’t have any problem.

If not then what am I looking for exactly. Schematic of the regulation circuit. This chip lm940 big cheap ceramic caps, I think. This capacitor must be rated over the same operating temperature range as the regulator and.

Whether this is really what they intend is unknown.

LM Datasheet(PDF) – National Semiconductor (TI)

Is the scope trace shown when under load? Tying down what manufacturers really mean can be a challenge. Less crucial is a picture of the output voltage waveform especially as we don’t datashewt what bad probing techniques you may have used.

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You have 5V on the schematic which can’t work.

Sign up or log in Sign up using Google. JohnLincoln God Member Posts: The suggested solution in that appnote, figure 7 vs. Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you datashewt read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. Do you also have the input capacitor 0.

National Semiconductor

Is your automotive environment 12V or 24V? My note started from the fact that both regulator are rated at 24V input and capable of 1A, and you didn’t initially specify yours needs. Perhaps I have misunderstood this specification? By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of dztasheet website is subject to these policies. Could that contribute to the oscillation?

What about with a simple resistor load at the same current, does it have the same problem? May be increased without bound to maintain regulation during transients. Or offer an alternative regulator that is more linear at high frequency As suggested in this answer? Also why do you have 18MHz 1.

Any advice or pointers will be much appreciated! I hope you know that the 2 are not properly the same parts, both are 5V regulators but the OKI is switching power supply, while the LM is linear one, the main difference for your use is heat dissipated.

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 be the instability trigger. Does anyone have any ideas how I might stabilize this output? 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. The datasheet specifies the drop-out voltage as 0.

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LM Datasheet(PDF) – National Semiconductor (TI)

You quote the ESR at kHz. In second case the OKI is highly suggested. For reference, this is the LM datasheet.

As, if anything, your ESR may be too high it seems I’d try another cap in parallel. Sign up using Facebook. I believe that I have conformed to the guidelines in the datasheet. Your oscillations are at 18 Mhz where the ESR is hopefully very low. CuF is an SMD tant: Anything with that rating or higher is fine.

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Have you taken their compulsory advice re the output capacitor?

Alas the data on minimum ESR is rather 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. I live in Lincoln. I read the data sheet for the LM and understand I need two capacitors one on the input and one on the output. As a general rule, the higher the voltage rating the larger the size so a 0.

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