Decent 24 volt Pic power supply

[rwskinner]

Just about everything I deal with is powered by 24 volts.

Something I hadn't found much information on is a good, industrial, 5 volt power supply that will allow 150-200 ma. or so to run a pic and a few components.

It would have an Automotive type 24 volt nominal input. For example, powered from a 24 volt power system on an industrial engine with a standard battery and alternator charging system.

Most of these range 18 to 30 vdc and are pretty noisy due to the alternator. I have seen numerous people stretch a 7805 out that far but I would be leary of the reliability.

There thousands of switchers out there, and some of them require more components than the main application circuit. The last couple I picked out, looked simple on paper, until I started pricing inductors and such, wow!

Not being real familiar with switchers I was wondering if anyone here had there favorite power supply they could recommend.

[sayzer]

... I have seen numerous people stretch a 7805 out that far but I would be leary of the reliability...

What is it you need with reliability?

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[rwskinner]

The Heat that thing dissapates plus the fact that it's maxed on input voltage and a little over for numerous configurations.

Are you saying that a 7805 can be ran reliable with 28 to 30 volts pulling 200 ma? I don't know, I'm asking.

[Squibcakes]

Skinner,

I've used 7805's and a high wattage dropping resistor to get 24V down to 5v... The 7805 works well (even when running very hot). They have thermal protection built in for when it gets too hot.

I've also made my own switcher circuits (Maxim makes some really good ones) which use a single IC and a few components. This method is more educational though.

You could try this PCB mount 24VDC-DC regulator (200ma) 1W --- SPRN01N-05 ----
Costs about A$20. Do a google to find the specs on it. it maybe just what your after. There is a 3W type with a wider input voltage too.

I haven't used them yet but plan to in the future.


Cheers
Squib

[sayzer]

If the case is high input voltage, then just use one 7818 or 7815 to drive 7805.

7818 or 7815 allows higher input voltage and in your case can make even better protection for 7805.


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[Acetronics2]

May be here ????

http://www.dimensionengineering.com/DE-SWADJ.htm

or here :

http://www.dimensionengineering.com/DE-SW0XX.htm

Alain

[rwskinner]

Thanks for all the comments and suggestions. I surely could run the two linears back to back like that and get away with it. Overall, a good simple switcher would still be the best bet as far as heat and effeciency. I break down and build some protos when I get time and come up with one for my library.

Again, Thanks to all and have a Merry Christmas.

[Ron Marcus]

I had a client project that ran on 24 volts AC and needed a good 12 volt supply for a camera, then 5 for a PIC. I used a switching regulator from National with a minimum number of parts to drop to 12 VDC. As I recall, the regulator didn't even get warm to the touch with 400 mA of current draw!