Atmega328p Breakout PRO

The Atmega328p Breakout Board has been out of stock for a while. I have half of the new components in hand, and the PCBs have been shipped and are on their way. The rest of the components will be ordered in the next couple of days and, if it’s like the last time I ordered, it will arrive the next day. Friday is Good Friday so I have to keep that in mind, and hope that everything comes in by then. I’ve made the decision that I will no longer sell unassembled kits so I hope I can use this long weekend to put them together so I have a decent stock ready for the next week.

Anyways, while I’ve been waiting for the new batch, I’ve been working on something else…

draft1To the right is the first draft of the Atmega328p Breakout Pro. The current base version will likely drop the ISP header. The new Pro version will sport the ISP header, in addition to a voltage regulator circuit. As I talked about in the last post about voltage regulators, I’ve been using my AMS1117 voltage regulator boards with my Atmega328p Breakouts in my own projects. With the built in regulator on this Pro version, I won’t need that extra board. The regulator I’ll be using this time is the NCP1117.

I believe the NCP1117 is the same regulator as the one on the Uno, or at least similar. It can output a fixed 5v at 800mA, even though at 800mA it’s best to just use another supply if you’re driving things that need that much current. When I was learning about PLCs, I was taught to separate the power supplies between the control unit (the PLC) and the actual peripherals (sensors, indicator lamps, etc). I don’t see why that lesson can’t be applied to Arduinos, even if they draw less current than a PLC.

I’ve added in the reverse input voltage protection diode so the total drop out is roughly 2v, just like on the Arduino. You’ll need to supply it at least 7v to get the 5v, and I’d limit the input to 12v tops just because of heat dissipation.

I’ve been trying to find out if it’s acceptable to have an external voltage applied on the output of the regulator. I want to be able to apply an external supply to Vcc (the output of the regulator, and the input power supply of the microcontroller). That way, you could use a battery or supply that’s already in the operating voltage range of the Atmega328p (1.8-5.5v). I’ve been looking at some Arduino and Adafruit schematics and it looks like you can, if you consider USB Vcc as an external 5v supply. They have it connected to the same 5v net as the output of the regulator (although the Adafruit schematics use a different regulator). I’ll keep researching and probably put together a prototype demo circuit and see what happens.

That’s it for now! Thanks for reading and I hope you’ll stop by my Tindie store and pick up some of my Atmega328p Breakout Boards when they’re back in stock!

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