Learning how to build driver circuits--any suggestions?

[gfang]

Ok, so maybe its a little over my head right now, but I would like to learn how to build boost and buck circuits to use with some of my LED projects. I know some basic electrical theory and I learn pretty fast, but I dont have time to go back to school right now. I have some of the tools I need already so can anyone point me towards a good resource for learning electronics and learning DC to DC convertors and such?

I have tried this once before, but I lost interest. While the projects in my book were designed to teach the fundamentals, they didnt do much with LED's, mostly with audio and such. Of coarse I should have stuck with it because many of the components and certainly the theory apply to all sorts of stuff.

Any recomendations for on-line resources? I probably need to start at a level that assumes I just dont know anything. What are those colored bands on the resistors for again?

 

[TMorita]

I would recommend looking in the DIY electronics forum.

Toshi

 

[chris_m]

A good place to start is looking at the datasheets for converter chips. Most have reference circuit diagrams, they often have component selection guides, and some even have information on PCB layout.

 

[joedm]

Here's the link to CPF University :

http://www.candlepowerforums.com/vb/showthread.php?t=53985&highlight=CPF+University

And yes I also think the data sheets for the various converters are a good start. A lot have diagrams for different applications.

 

[yellow]

You go tho THIS SITE:
http://www.national.com/appinfo/power/
(or the comparable ones from the other makers like Linear, ...)

type in Your data,
and get a few hits in return.
Then look at the global data (= efficiency, physical size / number of legs, needed parts, ...)
and decide which one to get.
Then download the datasheet and read a bit. There is really ANYTHING explained and usually also some circuit layouts shown.
Start with these and "gow up" to build such devices to Your needs.

PS: imho it is best to purchase ready made circuits, because they run, are much smaller than the one homemade, use perfect tiny parts that are hardly to get, usually are priced same of lower than the parts purchased by oneself.

 

[sysadmn]

Maxim and National both have good appnotes on power supply design. Let me know if you can't find them, and I'll dig up the numbers. (Hit: google "power supply tutorial application notes site: national.com" or similar. You can also use "led driver".) Even better, National has an "Analog University" with online courses: http://www.national.com/AU/design/.

As yellow pointed out, most vendors have a parametric search - choose Vin, Iout, etc, and get a list of chips. Unfortunately, until you know what a reference design looks like, it won't help much. (Buck, Boost, Switching vs Linear, dropout voltage, etc). Most distributors (digikey & mouser, for example) also have this. It's harder with distributors because you have to guess the magic keywords (linear regulator vs led driver vs power converter); and the keywords can be different for each chip vendor.

I also like National's interactive design tools: http://webench.national.com/appinfo/webench/scripts/my_webench.cgi It will do some of the parametric selection for you, select external component values, and output a bill of materials. In the US, for ~$30 more, they'll build the design (on a bigass board, unfortunately) and send it to you!

No, I don't work for National - I learned them in school, and check there first. The baby duck syndrome.