I am having a little trouble with the power input of the pro mini.
The symptom is that if I power the board with more than 6v to the RAW pin it drops the output voltage VCC to 3.3v. I am assuming that this is also affecting the internal voltage, but haven't verified.
If I use 5v power input on the RAW pin then everything works normally. ie.e 5v output on the VCC and to the digital output pins.
For bench testing I am just hooking it up to a breadboard power regulator that supplies 5v from a 12v input source. This is working fine when I connect this power to the RAW of the pro mini .I want to use this 12v input source for my Pro-Mini using the on-board regulator.
Here is what I am planning on doing to fix the issue.
- Install a voltage regulator on a PCB. The L7805CV is what I plan to use.
- I will connect the 12v input to the input of the L7805CV and then the 5v output to the RAW of the pro mini.
I know how to get it to work. What I want to do is make sure I am doing something that is optimum, or see if I am missing something critical regarding the input voltage. The on board regulator is working, it is just working at 3.3v.
I have another pro mini and it behaves the same way. Maybe the wrong voltage regulator is on the board? Hard to believe if it is happening on both Pro Mini that I have.
I thought maybe I have the 3.3v pro mini. The PCB on the pro mini is stamped with 5v on the VCC pin. It is advertised as a 5v 16mhz pro mini. It is possible that it is misrepresented both from the seller and on the PCB. Is there a way to check for sure on the chip or PCB of the pro-mini to make sure it is the 5v version?
It has been running fine for 3-4 days non stop with 5v input on the RAW and measuring 5v output on the VCC. I seem to recall that supplying lower than 6v to RAW will bypass the on board regulator. is this correct? If so does supplying 5v to the RAW cause more trouble than just connecting my 5v to the VCC?
I am happy I can get it to work. I am not happy that I don't really understand why it is behaving this way.
Any advice is appreciated.