Better 5 volt power supply
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I have always used the 7805 voltage regulator to provide 5 volts from a 12
volt power supply. As numerous posts have indicated, this is a somewhat
inefficient way to proceed. In a recent project, I was plagued by the heat
produced by using the 7805. In searching for a better solution, I cam across
the LM2675-5.0 simple switcher step down regulator from National
Semiconductor. NS also offers an evaluation board for $8.00 plus S/H. This
board is approximately 1.5" x 1.5" in size with all surface mount components
save for the connector. The board is rated at 1 amp. I purchased one and was
pleasently supprised with it's performance. It certainly eliminated my heat
problem.
Now I would like to build my own using all surface mount components. The
problem is that the circuit requires a 47uH inductor that is not available
from the usual mail order outfits like DigiKey and Mouser (to name a
couple). Does anyone have an idea where I might find such a critter? I have
tried the on-line part search route with no luck. I would like to find a
location that would sell me 10 at a time. By the way, all the simple
switcher ICs seem to require these rather specialized power inductors.
Any suggestions would be appreciated as would receiving a copy of your
response.
TIA
Vic
________________________________________________________
Victor Fraenckel - The Windman vfraenc1@n...
KC2GUI www.windsway.com
Home of the WindReader Electronic Theodolite
Read the WIND
volt power supply. As numerous posts have indicated, this is a somewhat
inefficient way to proceed. In a recent project, I was plagued by the heat
produced by using the 7805. In searching for a better solution, I cam across
the LM2675-5.0 simple switcher step down regulator from National
Semiconductor. NS also offers an evaluation board for $8.00 plus S/H. This
board is approximately 1.5" x 1.5" in size with all surface mount components
save for the connector. The board is rated at 1 amp. I purchased one and was
pleasently supprised with it's performance. It certainly eliminated my heat
problem.
Now I would like to build my own using all surface mount components. The
problem is that the circuit requires a 47uH inductor that is not available
from the usual mail order outfits like DigiKey and Mouser (to name a
couple). Does anyone have an idea where I might find such a critter? I have
tried the on-line part search route with no luck. I would like to find a
location that would sell me 10 at a time. By the way, all the simple
switcher ICs seem to require these rather specialized power inductors.
Any suggestions would be appreciated as would receiving a copy of your
response.
TIA
Vic
________________________________________________________
Victor Fraenckel - The Windman vfraenc1@n...
KC2GUI www.windsway.com
Home of the WindReader Electronic Theodolite
Read the WIND
Comments
>I have always used the 7805 voltage regulator to provide 5 volts from a 12
>volt power supply. As numerous posts have indicated, this is a somewhat
>inefficient way to proceed. In a recent project, I was plagued by the heat
>produced by using the 7805. In searching for a better solution, I cam across
>the LM2675-5.0 simple switcher step down regulator from National
>Semiconductor. NS also offers an evaluation board for $8.00 plus S/H. This
>board is approximately 1.5" x 1.5" in size with all surface mount components
>save for the connector. The board is rated at 1 amp. I purchased one and was
>pleasently supprised with it's performance. It certainly eliminated my heat
>problem.
>
>Now I would like to build my own using all surface mount components. The
>problem is that the circuit requires a 47uH inductor that is not available
>from the usual mail order outfits like DigiKey and Mouser (to name a
>couple). Does anyone have an idea where I might find such a critter? I have
>tried the on-line part search route with no luck. I would like to find a
>location that would sell me 10 at a time. By the way, all the simple
>switcher ICs seem to require these rather specialized power inductors.
>
>Any suggestions would be appreciated as would receiving a copy of your
>response.
>
>TIA
>
>Vic
Hi Vic -
The key to any of these specialized components, is to scan thought the data
sheets carefully. If you will note on the bottom of Page 8 of the LM2675
data sheet, you will note a coil designator. In this case it's L23. This is
the key to searching on the web sites of inductor manufacturers. I found
what you are looking for, and I'd be happy to further describe the
process. For the moment, here is the direct link to the Coiltronics web
site, and the specific component you require:
[noparse][[/noparse] http://www.coilcraft.com/ndo3316.html ].
This web site entry came not by chance. They develop this web pointer based
on the Simple Switcher KEY. Thus National's Coil reference L23 ==>
Coiltronics D03316. They quote a 1-500 price of $1.65 BUT they DO offer
free samples.
One brief note - use the BACK button which THEY provide in lieu of you
browser's back facility. Failure to do so brings about confusion in the
ordering of pages.
Regards,
Bruce Bates
>Now I would like to build my own using all surface mount components. The
>problem is that the circuit requires a 47uH inductor that is not available
>from the usual mail order outfits like DigiKey and Mouser (to name a
>couple). Does anyone have an idea where I might find such a critter?
Apologies - COILCRAFT not COILTRONICS as my earlier post read.
Sorry
Bruce
find these are as cheap as do-it-yourself when you figure in the labor.
Regards,
Al Williams
AWC
* Floating point math for the Stamp, PIC, SX or any microcontroller:
http://www.al-williams.com/awce/pak1.htm
>
Original Message
> From: Vic Fraenckel [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=wvu0B53HqLdxMqr_KMINiGvzDPzXgF0RlFwjJX2o6jHSVCTz22mB8fA3yCwf4Dpc3TIKF-4l4V2-IjM-BvY]vfraenc1@n...[/url
> Sent: Saturday, December 23, 2000 5:07 AM
> To: Stamp Mailing List
> Subject: [noparse][[/noparse]basicstamps] Better 5 volt power supply
>
>
> I have always used the 7805 voltage regulator to provide 5 volts
> from a 12
> volt power supply. As numerous posts have indicated, this is a somewhat
> inefficient way to proceed. In a recent project, I was plagued by the heat
> produced by using the 7805. In searching for a better solution, I
> cam across
> the LM2675-5.0 simple switcher step down regulator from National
> Semiconductor. NS also offers an evaluation board for $8.00 plus S/H. This
> board is approximately 1.5" x 1.5" in size with all surface mount
> components
> save for the connector. The board is rated at 1 amp. I purchased
> one and was
> pleasently supprised with it's performance. It certainly
> eliminated my heat
> problem.
>
> Now I would like to build my own using all surface mount components. The
> problem is that the circuit requires a 47uH inductor that is not available
> from the usual mail order outfits like DigiKey and Mouser (to name a
> couple). Does anyone have an idea where I might find such a
> critter? I have
> tried the on-line part search route with no luck. I would like to find a
> location that would sell me 10 at a time. By the way, all the simple
> switcher ICs seem to require these rather specialized power inductors.
>
> Any suggestions would be appreciated as would receiving a copy of your
> response.
>
> TIA
>
> Vic
>
> ________________________________________________________
>
> Victor Fraenckel - The Windman vfraenc1@n...
> KC2GUI
> www.windsway.com
>
> Home of the WindReader Electronic Theodolite
> Read the WIND
>
>
>
>