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5V regulator outputting 5.9V and more.

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MagicSmoker:

--- Quote from: floobydust on December 08, 2019, 10:15:12 pm ---LM2931 is an old 1st gen LDO, finicky about the output capacitance (value and ESR) and I would use something else. ...
--- End quote ---

Yep, this. I like the NCP5501 series of LDOs because they are pin-compatible with the 78xx series and have much more relaxed ESR/min. capacitance requirements. The LM2931 and xx1117 series should be left to the surplus bins and stocked only for replacement purposes.

james_s:
There's nothing really wrong with them, regardless of what part you use it's prudent to study the datasheet carefully. All components have limitations and this is a classic case where RTFM would have avoided the whole issue.

floobydust:
The LM2931 has more traps than usual. Noobs use a MLCC or polymer output capacitor and have troubles, especially in cold weather.
Jim Williams did a nice write up on using short PCB traces a few mm long to add ESR, have to dig for that LT app note.

wraper:
Apparently LM2931 from different vendors are not equal. Say according to ON semi datasheet it does not have any problems with extremely low ESR (MLCC). But according to TI, it should not be to low. On the other hand, TI can tolerate double ESR on the high side. IC schematic in the datasheets has some differences too.

wraper:

--- Quote from: floobydust on December 09, 2019, 04:45:15 am ---The LM2931 has more traps than usual. Noobs use a MLCC or polymer output capacitor and have troubles, especially in cold weather.
Jim Williams did a nice write up on using short PCB traces a few mm long to add ESR, have to dig for that LT app note.

--- End quote ---
More like little problems with half decent MLCC (given added series resistance or using LM2931 from ON semi) and big problems with aluminium electrolytic at low temperature according to those charts. It actually recommends poly cap (OS-CON).

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