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Electronics => Electronics => Topic started by: Admin on January 15, 2009, 08:10:39 AM

Title: need 3.3V LDO volt reg SMD with reverse polarity protection
Post by: Admin on January 15, 2009, 08:10:39 AM
I'm having serious trouble finding a:

voltage regulator
surface mount
3.3V
200mA+
low voltage drop LDO
reverse polarity protection
thermal shutdown

Anyone know of a part number they can point me to? Mouser/Digikey don't include reverse polarity in the search option and I've gone through tons of datasheets already . . .
Title: Re: need 3.3V LDO volt reg SMD with reverse polarity protection
Post by: izua on January 15, 2009, 09:34:03 AM
what about switching mode regulators? they don't do anything if you drain current out of the input (as far as i know and tested), are efficient and most have thermal shutdown.

lm2576 comes in both smt and th versions. the downside is that it needs a few parts around it, and only this combination assures the rev polarity protection.
Title: Re: need 3.3V LDO volt reg SMD with reverse polarity protection
Post by: fuzzyt on January 15, 2009, 10:43:30 AM
Not sure it covers reverse polarity protection, but everything else seems to be in order...

http://www.st.com/stonline/books/pdf/docs/2572.pdf

Title: Re: need 3.3V LDO volt reg SMD with reverse polarity protection
Post by: TrickyNekro on January 15, 2009, 12:04:59 PM
I think Schottky diodes have a drop down voltage around 0V15 to 0V45....
That will do... unless you are so space and cost restricted.... :P
Title: Re: need 3.3V LDO volt reg SMD with reverse polarity protection
Post by: want2learn on January 15, 2009, 01:33:28 PM
Have you looked at Micrel's website http://www.micrel.com/index.do
They have a regulator which probably suits your needs 'MIC5209-3.3YM' . As far as I can see it meets all of your needs and is available in a couple of different SMD packages. :)

As for where to buy, you can check the availability on their website.
The only place I looked was (the dreaded) Digikey. Their prices aren't that bad but I've got to agree with your comments about their nosey policy >:(

Sorry I don't know how to post those fancy links I see others using
Title: Re: need 3.3V LDO volt reg SMD with reverse polarity protection
Post by: Admin on January 15, 2009, 11:46:02 PM
thanks want2learn!!!

The MIC5209-3.3YS seems to be *exactly* what I was looking for.

futureelectronics.com appears to be selling them at $0.69 each.
Title: Re: need 3.3V LDO volt reg SMD with reverse polarity protection
Post by: pomprocker on January 16, 2009, 05:48:11 PM
aww man I just came back to this post to tell you about Micrel too. Guess I'm too slow