24W DC to DC converter

The input voltage range includes the output voltage, and that suggests searching for a "buck-boost" controller, or a "SEPIC" controller. Try the usual suspects: Linear Technology, Maxim, ... Their web sites will have product data sheets and ap notes. See, for example, Maxim ap note 1161 for a somewhat similar design The cost will depend heavily on how many you want to build; one-off, you may have some trouble making it for $3.40. You didn't mention if you want the output isolated from the input or not, nor what efficiency you'd like to attain, by the way.

Cheers, Tom

Thanks for ur replay Isolation is not required. I am going to use it for car audio, so ground terminal will be same for i/p and o/p. And the efficiency should be more than 75%..

Did you try National's online design bench? Go here:

-mpm

This is a non-sequitur. First, you say you want an input voltage range from 3.3V ~ 33V or something, with a 12V output, then you say it's for "car audio."

This doesn't follow, because cars already have 12V nominal (usually closer to 13.5~14.2V), and it's not usually "regulated", but merely protected from the hash and spikes that come with a car supply.

What are you really trying to accomplish? Get your homework done for you so you don't have to do the actual work?

Maybe ask the teacher, "Where am I supposed to get these things? Why are you giving me an assignment when I don't understand its fundamentals?" that sort of thing.

And please learn to trim and bottom-post.

Good Luck! Rich

Not obvious why you are doing this. If you are concerned about somebody hooking up a 28V boost battery, the radio would be the last thing I would worry about. However, some kind of over voltage protection would be easy enough to come up with. As for the 9.5 Volts, good time to turn the radio off; the car might still start.

Tam