Re: Efficiency of SMPS design.

From: Denis Gleeson (dgleeson-2_at_utvinternet.com)
Date: 06/10/04 

Date: 10 Jun 2004 02:11:38 -0700

Hi Guys

Thanks for the help.

Joerg can you recommend a fast fet for this cct. The data *** doesnt
propose one so I kept to a transistor.

Do you have a number for Fred Embuscado?

Ok My diode choice is wrong. Im not sure that a 1N4148b is the
solution. Its not a schotky and I dont think it could source the
current required into the coil. Ill find a suitable schotky.

Time for a new Transistor and diode.

The inductor size is confusing me.
I worked out the value as per the application note

http://www.national.com/an/AN/AN-1066.pdf

Ill need to look at the inductor selection some more

thanks.

Bye for now.

Denis

Joerg <notthisjoergsch@removethispacbell.net> wrote in message news:<MnKxc.68785$v16.67479@newssvr29.news.prodigy.com>...
> Hi Denis,
>
> That regulator worked like a champ for me. Three thoughts:
>
> A 2N2905 may not be the ticket here. You need a fast FET.
>
> Also, these fast reg chips cannot easily be breadboarded. It must be an
> RF circuit type of build, whether that is a prototype or a PCB. No long
> traces or wires.
>
> National has a great forum on their site for dessigners of switchers.
> They are very responsive and you don't even need password, sign-up or
> anything. Select "Power", then "Discussion Forum". Or call and ask for
> Fred Embuscado. I wish that all companies were as customer oriented as
> National is. Big cheers to them.
>
> Regards, Joerg
>
> http://www.analogconsultants.com

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