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Help selecting components for MAX641

S

Simon

Jan 1, 1970
0
I am planning on using a Max641 step-up converter. However as a
beginner, I am finding it difficult to choose the external components
- have studied Maxim's data sheet, but still a bit confused about what
Mosfet, inductor and capacitors to go for.
Can anyone make any suggestions. The 5V output will be 1A maximum
current and as well as the rest of the circuit, needs to power a PIC
mcu (does that mean I need to be concerned with the
smoothness/ripple)?
If you need any more information about the requirements, please ask.

As I said, I am a beginner and that includes soldering skills, so
preferable parts that are not too miniature (surface mount is OK but I
have trouble with the really tiny ones). And I would hope to be able
to use parts that are readily available from RS or Farnell in Europe.

Thanks in advance for any help.

p.s. Alternatively if anyone has an alternative suggestion than the
Max641, I would be interested to hear - it will use 2xNiMH 1.2V AA
equivalent batteries, and as I said above, should provide 5V, 1A
output. With minimum external part count, not too miniature and as
efficient as possible.
 
J

James Meyer

Jan 1, 1970
0
p.s. Alternatively if anyone has an alternative suggestion than the
Max641, I would be interested to hear - it will use 2xNiMH 1.2V AA
equivalent batteries, and as I said above, should provide 5V, 1A
output. With minimum external part count, not too miniature and as
efficient as possible.

Go to Linear Technologies web site and look at the products there. Then
get a free copy of their software, switcher cad, to play with. The cad program
will let you construct (simulate) any of their chips along with real-world
components that you can buy.

Jim
 
F

Fred Bloggs

Jan 1, 1970
0
James said:
Go to Linear Technologies web site and look at the products there. Then
get a free copy of their software, switcher cad, to play with. The cad program
will let you construct (simulate) any of their chips along with real-world
components that you can buy.

Jim

Instead of shooting your pig mouth off with a bunch hot air
generalizations, why don't you do that and walk the OP though a design,
posting your simulation resluts [sic] to abse....
 
P

Paul Burridge

Jan 1, 1970
0
Instead of shooting your pig mouth off with a bunch hot air
generalizations, why don't you do that and walk the OP though a design,
posting your simulation resluts [sic] to abse....

Oh-oh! Someone's run out of their meds again!
 
J

John Fields

Jan 1, 1970
0
Instead of shooting your pig mouth off with a bunch hot air
generalizations, why don't you do that and walk the OP though a design,
posting your simulation resluts [sic] to abse....

Oh-oh! Someone's run out of their meds again!
 
P

Paul Burridge

Jan 1, 1970
0
And someone else is looking for their fair share of abuse?^)

Water off a duck's back, old boy; water off a duck's back. ;-)
 
J

James Meyer

Jan 1, 1970
0
James said:
Go to Linear Technologies web site and look at the products there. Then
get a free copy of their software, switcher cad, to play with. The cad program
will let you construct (simulate) any of their chips along with real-world
components that you can buy.

Jim

Instead of shooting your pig mouth off with a bunch hot air
generalizations, why don't you do that and walk the OP though a design,
posting your simulation resluts [sic] to abse....

Generally when someone goes to the effort of posting a well thought out
reply that contains explicit recommendations, the original requestor will come
back with some reason why none of the information is of use to him and tell us
that he will continue to pursue his original direction no matter how likely it
appears to us to be fruitless. (Burridge syndrome)

I'd rather offer a quick look at a different direction and then, if the
original requestor shows some interest or needs more details, provide a
follow-up.

You, on the other hand, tend to make pronouncements from on high and
expect the whole world to fall down at your feet, believe every word, and kiss
your ass for even bothering to speak to them.

That just ain't my style, Clyde.

Jim
 
F

Fred Bloggs

Jan 1, 1970
0
James said:
You, on the other hand, tend to make pronouncements from on high and
expect the whole world to fall down at your feet, believe every word, and kiss
your ass for even bothering to speak to them.

That just ain't my style, Clyde.

Jim

You only read it that way because you they released you from treatment
too early. See a lawyer about suing your psychiatrist.
 
K

Ken Smith

Jan 1, 1970
0
I am planning on using a Max641 step-up converter. However as a
beginner,

Perhaps the Max641 is above the beginner skill level. There are switcher
chips where the power transistor is built in. I'd suggest you look at
these because in general they are easier to work with.

If you are using the MAX641, it looks like you need a fairly large
(mechanically) 50uH (or so) inductor.

I'd suggest against using this chip because it doesn't have a current
limit. This means that unless you add your own somehow, one brief short
will destroy the circuit.
p.s. Alternatively if anyone has an alternative suggestion than the
Max641, I would be interested to hear - it will use 2xNiMH 1.2V AA
equivalent batteries, and as I said above, should provide 5V, 1A
output. With minimum external part count, not too miniature and as
efficient as possible.

Could you live with an unregulated 4xNiMH supply?
 
J

James Meyer

Jan 1, 1970
0
You only read it that way because you they released you from treatment
too early. See a lawyer about suing your psychiatrist.

"... you they released you ..."?

Take a nap, Fred. You're blithering.

Jim
 
B

Bob Wilson

Jan 1, 1970
0
Go to Linear Technologies web site and look at the products there. Then
get a free copy of their software, switcher cad, to play with. The cad program
will let you construct (simulate) any of their chips along with real-world
components that you can buy.



Ahh yes. SwitcherCad. AKA "Switchmode Power Supplies for Dummies". You too can
design a SMPS without understanding anything about it! :)\

Bob.
 
T

Tony Williams

Jan 1, 1970
0
Bob Wilson said:
Ahh yes. SwitcherCad. AKA "Switchmode Power Supplies for
Dummies". You too can design a SMPS without understanding
anything about it! :)\

Steady on, Bodge. LTSpice is my favourite toy atm.
 
F

Fred Bloggs

Jan 1, 1970
0
Bob said:
Ahh yes. SwitcherCad. AKA "Switchmode Power Supplies for Dummies". You too can
design a SMPS without understanding anything about it! :)\

Bob.

Even that is not enough assist for some people...now you have all sorts
of dummies like the "bit heads" thinking they can do this on their own.
 
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