In my last post, I talked about assembling my two new PCB designs. In this post, I’ll talk about the results of some tests with the AMS1117 dual fixed voltage regulator board.
As I was assembling the board, I had realized that I hadn’t accounted for the voltage drop of the diode. It wouldn’t be an issue, except that I wrote that the maximum drop out of the AMS1117 is 1.3v on the back of the board. Theoretically, there’s a dropout of 2v with the reverse polarity protection diode in the circuit, which is about the same dropout as the LM7805 voltage regulator. I’m glad I put in the diode though, since I’ve accidentally connected the battery backwards a few times already.
Anyways, I don’t have a variable voltage supply so I built an LM317 variable voltage regulator on a breadboard for this test. The test was to ramp up the voltage to see when the 3.3v and 5v outputs would appear so I can measure the dropout.
You can find my test notes here. Basically, I found that the total dropout with the diode for the 3.3v regulator to be 1.74v and 1.59v for the 5v regulator. I’d round up the total dropout for both to 1.9v, or 2v to make things easier. I chose the AMS1117 instead of the LM7805 because of the lower dropout, but I forgot about the protection diode. I’m still glad I went with it because it reduces the board size significantly, and the SMD soldering is fun.
Test results for the ATmega328p Breakout Board should be posted soon. It was a pretty basic test, which it passed. Yay.
Thanks for reading!