Common step-down switching regulator

Can you please suggest one or more ICs for general use as a
step-down switching voltage regulator? This is for general stock
to be used as needed for a variety of projects. There's a
plethora of such devices out there, but what I'm looking for is a
type that has become popular enough to be regarded almost as an
industry standard and be available anywhere (and at a low price),
in much the same way as the linear 78xx series and the LM317.
Desireable specs would be -

1. Low external component count
2. Max input voltage around 40V
3. Max load current 1A or more
4. Fixed or adjustable output voltage
5. Output voltage range 5-15V or wider
6. Non-SMD if possible, but not essential

 

Last time I needed such a thing I found the MC34063. Looks like to fit your
requirements pretty well.

petrus bitbyter

 

Most ubiquitous and ridiculously cheap MC34063A and copies, but it is
looking a bit long in the tooth. It's slow and transistor output. So you
will need larger inductors and capacitors, and dissapate more heat, than
more modern devices.

It is frustrating that there don't seem to be any newer parts anywhere
near the price.

 

Thanks. I'd already looked at the LM25575 but the external
component count is a bit more than I'd like, though it seems to
have regulation and efficiency than the LM2575. I think I've seen
the 2575 used more than once before, but a browse of the NatSem
site didn't bring it up immediately, so it didn't come to mind
until you suggested it. Looks like it will do nicely. Thanks
again.

 

Thanks. I'd already saved the datasheet of the MC34063. If it's
widely available, it's a good candidate.

 

Thanks. By transistor output, I take it you mean bipolar. The
datasheet I have of the MC34063A is by ON Semi. It gives only a
limited amount of info about the efficiency and dissipation.
Maybe I should download one from another manufacturer.

 

If you have that kind of requirement, there are definitely some
offshore-only parts that are probably near the price (probably lower
maximum input voltage). Try tearing apart some consumer goods. Also
some of the NS switchers have been cloned.

 

I'm using an NCP3063 which is a higher speed upgrade on a current
project. It's useful where you need buck or boost.

My unit has low power 5V buck and a 24V boost to power the sepic
circuitry as well as USB charger outputs. All bult around the NCP
3063. The MC34063 wasn't good enough on the first prototypes.

 

I've used that one too and you're right. Still only 150kHz and bipolar
though. Might be a good fit for the OP.

 

It's cute all right, but not as cheap as I'd like it to be.

That's real neat but, as you say, way too expensive for the kind
of use I have in mind. It's certainly worth keeping in mind for
other purposes where price is not an important factor.

 

The NCP3063 looks like a good trade-off between price and
performance, and the boost option is attracttive. Perhaps a mixed
stock of it and the MC34063 will be a good idea.

 

The R-78 series would be perfect (~95% efficiency, through-hole
option, no external parts except the inevitable input-output
caps) but I couldn't find indicative prices with a quick search.
I expect they'll be a bit on the high side for my purpose and
also not easily available everywhere.

 

Thanks for all the replies, everyone. They were all on-topic and
really helpful - something that's all too often *not* the case on
Usenet.

I particularly appreciate your keeping in mind the criteria of
low cost and easy availability. The latter is necessitated by my
location and work environment (I won't bore you with the details)
which is why I didn't just make a selection from the results of
my own searches. I hope you won't mind if I ask the same type of
questions about other devices from time to time.