Stamp power
Good afternoon,
I am using several stamps in a critical battery powered app.
I'd like to get a longer battery life; I haven't used the
2595/2574 type switchers before, but I have several laying in storage and
believe they would work well.
But, as I'm to use them for the first time, I have two questions:
1) There are several specially-made inductors made for the 25xx by
Schott, etc. But these are very spendy. Are they required, or what
other type of inductor could I use?
2) Is the placement of this inductor near a Stamp be critical-- I
don't know how much noise is radiated by them from these switchers, and
wouldn't want to cause any interference to Stamp pins used for
measurements.
Any comments on either of these two would be much appreciated.
Thank you for your time, have a pleasant evening,
Paul
I am using several stamps in a critical battery powered app.
I'd like to get a longer battery life; I haven't used the
2595/2574 type switchers before, but I have several laying in storage and
believe they would work well.
But, as I'm to use them for the first time, I have two questions:
1) There are several specially-made inductors made for the 25xx by
Schott, etc. But these are very spendy. Are they required, or what
other type of inductor could I use?
2) Is the placement of this inductor near a Stamp be critical-- I
don't know how much noise is radiated by them from these switchers, and
wouldn't want to cause any interference to Stamp pins used for
measurements.
Any comments on either of these two would be much appreciated.
Thank you for your time, have a pleasant evening,
Paul
Comments
What are 2595/2574 switchers? Are they ICs, and if so, what is the complete
part no?
Ray McArthur
My mistake, here is something more specific:
lm2595 1A switching supply (IC), and lm2574 0.5A switching supply
(IC). Extensive datasheets on the National website, and briefly in their
Analog and Interface Products Databook. I don't believe they mention
anything about noise from the inductor, or on the allowed inductor types.
But perhaps I just keep missing it...
Thank you,
Paul
On Sat, 8 Jul 2000, rjmca wrote:
> Hi Paul,
>
> What are 2595/2574 switchers? Are they ICs, and if so, what is the complete
> part no?
>
> Ray McArthur
>
>
>
>
>
>
>Good afternoon,
>
> I am using several stamps in a critical battery powered app.
>
>
> I'd like to get a longer battery life; I haven't used the
>2595/2574 type switchers before, but I have several laying in storage and
>believe they would work well.
>
> But, as I'm to use them for the first time, I have two questions:
>
> 1) There are several specially-made inductors made for the 25xx by
>Schott, etc. But these are very spendy. Are they required, or what
>other type of inductor could I use?
>
I just took a look at the datasheets for both the IC's you mentioned.
Neither one listed any Schott inductors. The LM2595 listed inductors from
Coilcraft, Pulse Engineering and Renco. The LM2574 listed ones from Pulse
Engineering, Reco and NPI(Europe). Page 19 of the LM2595 datasheet and page
16 of the LM254 datasheet have a sections on inductor selection.
> 2) Is the placement of this inductor near a Stamp be critical-- I
>don't know how much noise is radiated by them from these switchers, and
>wouldn't want to cause any interference to Stamp pins used for
>measurements.
>
On page 21 of the LM2595 datasheet is a discussion on placement of the
inductor.
>
> Any comments on either of these two would be much appreciated.
>
> Thank you for your time, have a pleasant evening,
>Paul
>
>
I hope this helps.
Bob
> 1) There are several specially-made inductors made for the 25xx by
> Schott, etc. But these are very spendy. Are they required, or what
> other type of inductor could I use?
*** I looked at Pulse Engineering's site, but could not find prices. From
looking at the 2574 data for a 5 volt fixed regulator, you need ~330 uH
inductor, (see the data sheet for Vin, Iout), rated for ~50 khz operation
and 0.5 amps DC. Its DC resistance should not exceed ~ 1 ohm, (this is
direct series loss). This type of inductor is usually wound on a ferrite
potcore, which provides some self shielding.
Some of my old app notes list some sources you might check for
price/availability:
Coilcraft
Cary, IL 800-322-2645
Coiltronics
Boca Raton, FL 407-241-7876
Murata Erie N. America
Smyrna, GA 404-436-1300
> 2) Is the placement of this inductor near a Stamp be critical-- I
> don't know how much noise is radiated by them from these switchers, and
> wouldn't want to cause any interference to Stamp pins used for
*** This is probably "try it and see". It's a good idea to keep the
switcher on its own circuit board. The voltage switching spikes are often
more noisy than the magnetic field. I have a 35 watt switcher within 1/2"
of a PIC with no problems.
Hope this helps,
Ray McArthur
PS: Have you checked the surplus houses for a suitable switcher?
Please see below...
On Sat, 8 Jul 2000, Robert Baxter wrote:
> At 03:05 PM 7/8/00 -0700, you wrote:
> >Good afternoon,
> >
> > I am using several stamps in a critical battery powered app.
> >
> >
> > I'd like to get a longer battery life; I haven't used the
> >2595/2574 type switchers before, but I have several laying in storage and
> >believe they would work well.
> >
> > But, as I'm to use them for the first time, I have two questions:
> >
> > 1) There are several specially-made inductors made for the 25xx by
> >Schott, etc. But these are very spendy. Are they required, or what
> >other type of inductor could I use?
> >
>
> I just took a look at the datasheets for both the IC's you mentioned.
> Neither one listed any Schott inductors. The LM2595 listed inductors from
> Coilcraft, Pulse Engineering and Renco. The LM2574 listed ones from Pulse
> Engineering, Reco and NPI(Europe). Page 19 of the LM2595 datasheet and page
> 16 of the LM254 datasheet have a sections on inductor selection.
That's true, the datasheet didn't list Schott except in one
mention. I believe I found more details through Digikey, with inductors
designed for virtually all National switchers. I'll look at the others,
as you suggest, perhaps the inductors are cheaper there?
>
> > 2) Is the placement of this inductor near a Stamp be critical-- I
> >don't know how much noise is radiated by them from these switchers, and
> >wouldn't want to cause any interference to Stamp pins used for
> >measurements.
> >
>
> On page 21 of the LM2595 datasheet is a discussion on placement of the
> inductor
They do talk about just simply experimenting with location to see
if there's any pickup, but in this case I really have no way of telling.
Perhaps I will have to just spend a bit of time with a probe
after all and use a brute-force method; or maybe even resort to shielding,
although that's the last thing I want to do here.
>
> >
> > Any comments on either of these two would be much appreciated.
> >
> > Thank you for your time, have a pleasant evening,
> >Paul
> >
> >
>
> I hope this helps.
> Bob
It does, thanks for your time and help,
Paul
>
>
>
>
>
On Sun, 9 Jul 2000, rjmca wrote:
> Paul:
> > 1) There are several specially-made inductors made for the 25xx by
> > Schott, etc. But these are very spendy. Are they required, or what
> > other type of inductor could I use?
>
> *** I looked at Pulse Engineering's site, but could not find prices. From
> looking at the 2574 data for a 5 volt fixed regulator, you need ~330 uH
> inductor, (see the data sheet for Vin, Iout), rated for ~50 khz operation
> and 0.5 amps DC. Its DC resistance should not exceed ~ 1 ohm, (this is
> direct series loss). This type of inductor is usually wound on a ferrite
> potcore, which provides some self shielding.
>
> Some of my old app notes list some sources you might check for
> price/availability:
>
> Coilcraft
> Cary, IL 800-322-2645
>
> Coiltronics
> Boca Raton, FL 407-241-7876
>
> Murata Erie N. America
> Smyrna, GA 404-436-1300
>
I'll do that, and take a look at Coilcraft, one I haven't checked
yet.
> > 2) Is the placement of this inductor near a Stamp be critical-- I
> > don't know how much noise is radiated by them from these switchers, and
> > wouldn't want to cause any interference to Stamp pins used for
>
> *** This is probably "try it and see". It's a good idea to keep the
> switcher on its own circuit board. The voltage switching spikes are often
> more noisy than the magnetic field.
Noted!
>I have a 35 watt switcher within 1/2"
> of a PIC with no problems.
35W? That's good, as 1) the stamp is essentially a PIC, and 2) I
will use max 8W. So hopefully this will work out fine.
>
> Hope this helps,
> Ray McArthur
>
> PS: Have you checked the surplus houses for a suitable switcher?
Always the first place I look[noparse]:)[/noparse]
Thank you Ray for your help, have a nice evening,
Paul
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