Some one could explain to me please the difference between the LP2992IM5-5.0/NOPB, LP2992IM5X-5.0/NOPB, LP2992AIM5X-5.0, LP2992AIM5-5.0? They all seems to be the same thing.
LDO LP2992 5V Naming
5vldo
Related Solutions
I have never seen ready-made ICs with such a feature.
There are, however, ICs that have a shutdown (or enable) input that might be used for such a feature when you add an external comparator and/or reference.
You might also want to consider building your own LDO, using a PMOS (or pnp) pass transistor, a reference (LT1431, LM4121-ADJ, LM4051-ADJ or even TL431 come to mind), some discrete components and some sort of 2nd comparator for the under-voltage lock out.
Take care about the regulator's stability (ESR of output capacitor must neither be too small nor too large, cf. "Tunnel of Death"). These links are helpful:
Short and good Application Note by NSC
A paper that offers some really good theroetical background
An entire thesis by the same author as the paper, also a good read
Building your own LDO has the disadvantage that you don't get features like thermal shutdown or short-circuit protection without additional effort, but it offers a great deal of flexibility (and it's fun).
It looks to me like a netlist/layout error:
If you are placing your fixed resistor on the dig pot footprint, it would also be messed up. Looks like you accidentally wired the CO+ and NO2- together and the NO2+ and CO- together so the LDO(Vout-Vadj) is not across a resistance as you believe.
Best Answer
If you look at the LP2992 datasheet, you'll see that the "A" versions have tighter tolerance on their specifications.
The "I" seems to denote industrial temperature range, although they never explicitly say this. They don't seem to offer any other temperature range anyway.
"M5" denotes the SOT-23 package.
The "NOPB" notation means "no lead" (RoHS-compliant).
However, I can't figure out what the "X" denotes. I suspect it has something to do with how the part is delivered on different kinds of reels for high-volume manufacturing.