Lower Cost switching power supply solutions?

I am basically looking to turn 13.8V car voltage into +/- 12-15V. It doesn't need to supply much power since its for pre amp circuitry.

Reading through TI's App notes, I found the UC2577-ADJ which is listed as a "simple step up voltage regulator"

It looks like all it needs are a few small components.

I am a little unclear of the inductor. The datasheet indicates that I need a 330uH inductor with a V * T rating of 250V*uS. The datasheet lists suggested units and their part numbers, but I am not sure if i'll find them in the normal electronic outlets. The chart in the data sheet lists lower valued inductors with increasing current requirements. I can't tell if this is due to the current ratings on the "recommended" parts, or is a requirement of the circuit.

Looking through my digikey catalog, the only inductors I see that even have a VT rating are rated in millihenries and have VT ratings of 1000 or more. can anybody who is familiar with this comment on whether more inducance and a higher VT rating are acceptable as long as I don't exceed the current rating of the inductor. I think the only job for the inductor is just to store energy, but I am somewhat new at this.

I am a little concerned with the quality of signal coming from something like this, I am assuming filter capacitors and additional voltage regulators along with the good power supply rejection of most new opamps will provide as much performance as can be expected in a car.

Are there generally major problems when using something like this, or is it as straightforward as the datasheet suggests?

Thanks in advance, and I'll understand if nobody has used anything like this before.



2001-02-01 2:43 am

Search in my replies. There are suggestions about simple self-oscillating power supplies for car applications. If it solves your problem, I will send an archive with the project for you or I will indicate the references.