AMS SOT 223 reg

tony_g

Senior Member
just wanted to get some verification of the top tab for this voltage reg AMS1117 5v

the datasheet says the top tab for the T0 252 is also v+ out so i just wanted to confirm with anyone who has knowledge of this or has used it that the same applies to the SOT 223 as this info is only printed directly above the other device.

would rather check first than assume it is, just incase it is a thermal heatsink of sorts instead.

thanks.

View attachment datasheet (1).pdf
 
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Goeytex

Senior Member
The info is not printed above the SOT-223 package, so the the tab for that device is not connected to "OUT". If the tab on the SOT-223 was electrically connected, it be would specifically noted in the datasheet. That means with the SOT-223 that the ground plane can be used for heat dissipation.
 

Dippy

Moderator
I'm not sure but looking at similar regs from other manufacturers (Diodes Inc, Linear and National) the tab of SOT-223 is connected to Vout.

A 5 second multimeter check to Pin2 will confirm. Best not to assume.
 

tony_g

Senior Member
ok thanks guys just thought i would double check before letting any smoke out lol, just gotta dig out the multimeter then, it went walkies during the house move.
 

Paix

Senior Member
I have three claw hammers, four or five tape measures and at least two lump hammers (18m2 type) because I was doing something and the options at hand were to spend inordinate time looking for what I needed or going to the big shed, buying a new one and getting on with the job.

You obviously need another multimeter . . . :)
 

tony_g

Senior Member
I have three claw hammers, four or five tape measures and at least two lump hammers (18m2 type) because I was doing something and the options at hand were to spend inordinate time looking for what I needed or going to the big shed, buying a new one and getting on with the job.

You obviously need another multimeter . . . :)
and i have now bought another one, $59 on clearance to $14 :D
 

inglewoodpete

Senior Member
...my local supplier gave me one free with a recent order >$100. Just a cheapie, but still handy to have. I think I'll get my wife to carry it in her handbag :):)
 

Paix

Senior Member
That would be the multimeter, or perhaps the claw hammer, Pete? Useful for those odd jobs about town, a very practical woman I can see. That and two multi-meters, you seem to have it made my old son.

I would concur with electcrically checking the tab for your own confidence, although the tab on the TO-252 package specifies the tab and pin 2 are connected, this note is specific to that package. I believe that the standard is that the tab is isolated or at ground unless otherwise stated, but have to agree that a statement one way or another for the SOT-223 package would have been helpful to remove any doubt from the situation.

With the average woman's handbag, you might never be able to find your multi-meter/claw hammer again unless you can get it to ring whist searching for it - don't forget it's off limits to other than the owner. I just hope there isn't a collection of such containers, which could raise the stakes considerably :)
 

JimPerry

Senior Member
Must admit - I've only got 3 (that I can find [sure I had 4]) - they seem to migrate, with Biro's and tape measures, to very dark coirners indeed. :confused:
 

Dippy

Moderator
Just put the connectors, display and controls on the outside of the handbag and then you won't need to go rummaging around.
Add the fact the the Missus will be highly unlikely to lose the handbag and you have an easily available multimeter.

Personally, I think it's always a good idea to do basic checks where possible. And it doesn't come much easier than checking continuity between tab and pin.
Sadly, data sheets contain errors now and then... and the spelling is getting wurse.
 

ashleylad

Member
Hey Tony, hope you are well.

I have used some of the AMS1117 parts recently which claim max 1A output. I can confirm that the large tab is VOUT. With soldering this to a suitable land of copper, the quoted max amp out is achievable. I have used a few on some PIC circuits, soldering across the rows of strip board and flooding the large tab to two tracks for heatsinking. Most of the circuits are only pulling a few hundred, just purchased them for their small footprint.

I hooked one up on a bench top psu first just to prove the pinout was correct.

Hope this helps.

Ash
 

ashleylad

Member
Goeytex, yes indeeed, part number AMS 1117 +5.0

See the attached photo, crude set up, 9 volts in and 4.98 volts out on calibrated work multimeter.

fluke.jpg

apologies for image clarity, taken on my entry level mobile/cell phone.

Been working in electronic manufacturing for over twenty years definitely a SOT-223 footprint!

cheers

Ash
 
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Paix

Senior Member
Many thanks for the clarification Ash. It seems a pity that the datasheet wasn't quite so unambiguous.
 

tony_g

Senior Member
hey ash, thanks for the confirmation on the tab. i bought a few of them in the 5v 1a version and am just patiently waiting for them to arrive.
eventually going to be powering a set of nav lights for my brothers new plane and i needed to look at small footprint with the whole design so smd all the way lol.
after seeing some of your pics of smd light circuits i thought i may as well give it a try :D just wanted to make sure i did not let any of the factory installed smoke out by assuming with the tab but thanks for the confirmation.
 

ashleylad

Member
Nice one Tony, best of luck with your new project, looking forward to seeing the finished circuit.

Don't really have the time these days to make diy pcbs, so end up using stripboard or similar. Most of my circuits recently have been a mixture of smt and through hole.

Ash
 
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