Hi, I've designed a simple Arduino-like board and have laid it out. As it stands, the circuit works fine, but I had a few queries regarding best practices.
Firstly, I have heard that it's wise to use capacitors to smooth the voltage coming in and out of a voltage regulator (5V regulator from DC source - 7.5 - 12v). How important is this? And what's the best way to calculate the necessary capacitance for such a purpose?
Secondly, should I expect any issues powering my board solely over external DC? I have noticed a few threads on this forum noting unexpected behaviour when using other DC as opposed to USB.
Many thanks, Mike. The article of yours answered a lot of questions.
To clarify, if I may, am I right in thinking that I should use a small ceramic cap (0.1uf) near the IC between PWR/GND and the larger cap (10-100nf) just inside the regulator (between it and the rest of the circuit)? IC-wise I just have an ATMega328P in there.
Most of the problems you see here stem from people using little 9V PP3 batteries and expecting them to power a car.
Those little batteries can only provide a relatively tiny current, and are barely capable of powering the Arduino itself.
As long as you use an external DC power source that can provide enough current for whatever it is you're doing then it is no different to running off USB. Better, in many cases, as the USB is limited to 500mA absolute maximum.
