Bring +5V to AVR: which solution ?

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Hello,

My code is almost done, so I'll start creating a prototype PCB (with eagle probably). Now comes the question on AVR and the power source. Is a 7805, like the ones found on most boards enough ? I found some boards using more advanced regulators (LM2594-5 for example). I'm looking for stability....
Bonus question: is there somewhere a basic schematic eagle file with PS, max232, crystal, JTAG, ISP ..... I tried several projects but couldn't find the "dream" one.

Thanks.

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7805 are quite fine, its biggest issue is efficiency. It requires a significant voltage drop. This is an issue if you using batteries (because it requires more input voltage) or if heat dissipation is an issue (power = voltages * amps). More efficient are low voltage dropout linear regulators. Even more efficient are DC-DC converters, but they require additional components.

If battery life and heat dissipation are not an issue for your application, go ahead with the 7805 as it's quite stable, inexpensive, and easy to use.

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Thanks. It will be powered from 220V, so no battery life to worry.... let's go with it then !

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I've used a really nice unit made by a company called traco power.
It'll take anything between 9 and 36 volts, and give you a really nice, stable, regulated 5v output. It also has the added bonus of giving you indefinate short circuit protection, and reverse voltage protection.
Just google Traco Power, and you should find them.

Tomorrow is the busiest day of my week.

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vthinsel wrote:
Thanks. It will be powered from 220V, so no battery life to worry.... let's go with it then !

7805 is quite good choice!
But I feel obligated to say, ask! Do you have in mind transforming 220V/AC to DC and transforming it to lower values (7805 input capable values)?
I don’t know the back side of your story but I wouldn’t like you to input 220V to 7805 ;(

Another idea is to use cell phone charger. Or similar AC to DC low voltage device, current 500mA-1A.
They can be found cheap in retail price!

I don’t know load of your device, you can always use different (separated) supply for uC to gain in stability in that part…

Matthew