[Mino]

Hello, what happens when too much current is drawn from an LM317
configured for 3.3V output? Does the output voltage decrease?

 

[legg]

Hello, what happens when too much current is drawn from an LM317
configured for 3.3V output? Does the output voltage decrease?

Yes.

This part has a data sheet that should answer most of your basic
questions.

http://www.national.com/ds/LM/LM117.pdf

RL

 

[Grant]

Coincidentally, I recently had reason to test a National LM317L/TO92
as a current limiter. It passes about 180 mA for a second or two, then
does this:

ftp://jjlarkin.lmi.net/LM317L_ilim.JPG

The duty cycle is sensitive to cooling, so it makes a sort of goofy
air flow sensor.

I have some voltage drop vs current data too, but I don't have it
here. I recall stuff like 1.4 volts at useful currents. I can post it
later if anyone is interested.

I like scope pictures+post-its. It's easier than fooling with USB
sticks and, in my opinion, looks better.

Photos lot quicker on older scope with a floppy drive

There's an app note or datasheet says they do that, nice to it's true.

Grant.

 

[[email protected]]

Photos lot quicker on older scope with a floppy drive

I guess! That's all we have. Have to dump 200K per trace to floppy, then
import the crap into Excel '07, which is a complete pig.

 

[JosephKK]

Easy enough to do, but customers won't PAY for such smarts.

...Jim Thompson

Bit of an odd thing to say, isn't the just stated performance of the
fan controller an exact counter-example to that assertion?

 

[Spehro Pefhany]

Pay for such smarts? We buy lots of fans, and I've stopped a lot of
them by hand, and I've never seen one blow up. We don't even pay extra
for non-blowing-up fans. Even the cheapest ones self-protect.


I remain surprised that nobody makes a good general-purpose current
limiter chip. It wouldn't even have to be a single-purpose part, just
one more current-set pin on an LDO.

John

Aren't the hot-swap controller chips pretty much that?



Best regards,
Spehro Pefhany